50 Genuine Synonyms for Sincerely in Letters and Speech

Sincerely does two very different jobs in English, and mixing them up is where most synonym confusion starts. As an adverb, it modifies a verb to show genuine feeling, as in “I sincerely apologize.” As a letter or email closing, it’s a formal sign-off with almost no literal meaning left in daily use — nobody reads “Sincerely,” at the bottom of an email and thinks about sincerity at all.

Because of that split, the best alternative depends entirely on which job you need. Genuinely, truly, and wholeheartedly work well inside a sentence, while Best regards, Warmly, and Yours faithfully belong at the bottom of a letter and would sound strange dropped into the middle of a sentence instead.

This guide covers both senses separately, so you can find a natural adverb replacement or the right closing for the tone of your message.

Best Synonyms for Sincerely at a Glance

What Does Sincerely Mean?

Part of speech: Adverb.

Sense 1 (adverb of genuine feeling): In a manner that is honest and free of pretense; truly. Example: “I sincerely hope you feel better soon.” Example: “She sincerely believed in the project’s mission.”

Sense 2 (letter/email closing): A conventional sign-off used at the end of letters and emails, largely stripped of its literal meaning through everyday use. Example: “Sincerely, Jane Smith.”

The two senses call for very different alternatives, which is why treating “sincerely” as a single word with one list of synonyms leads to awkward substitutions.

Word Family of Sincerely

• Adjective: sincere
• Noun: sincerity
• Adverb: sincerely

Origin and Etymology of Sincerely

Sincerely comes from the Latin “sincerus,” meaning clean, pure, or genuine. A popular story claims the word originally meant “without wax” (from Latin “sine cera”), supposedly referring to unblemished pottery, but most linguists consider this a false folk etymology rather than the word’s real origin. The reliable root is simply “sincerus,” meaning pure or unmixed, which extended naturally to mean honest or genuine.

Connotation and Tone of Sincerely

As an adverb, sincerely carries a warm, earnest connotation and slightly formal register, often used to add weight to an apology, belief, or hope. As a letter closing, it’s fairly neutral and standard rather than especially warm; it sits in a middle ground, more genuine-sounding than “Regards” but less overtly friendly than “Warmly” or “Best wishes.”

Synonyms for Sincerely by Context

For Genuine Feeling (Adverb Use)

Genuinely, truly, honestly, wholeheartedly, earnestly, heartily, truthfully.

For Formal Letter or Email Closings

Yours faithfully, Yours truly, Respectfully, Cordially, Best regards.

For Semi-Formal or Warm Closings

Warm regards, Kind regards, Warmly, Best wishes, All the best.

For Informal Closings

Take care, Thanks, Cheers (British informal).

50 Synonyms and Alternatives for Sincerely

1. Genuinely

Part of Speech: Adverb
Meaning: In a real, unpretentious way; truly felt.
Best Used For: Everyday sentences expressing honest feeling.
Example: “I genuinely appreciate your help.”
Nuance: Slightly more casual than sincerely, and just as natural in speech as in writing.
Synonym Strength: Very Close (adverb sense)

2. Truly

Part of Speech: Adverb
Meaning: In a true or accurate manner; genuinely.
Best Used For: Both emotional emphasis and formal closings (“Yours truly”).
Example: “I truly believe this will work.”
Nuance: Works in both the adverb sense and as part of a letter closing, unlike most alternatives.
Synonym Strength: Very Close

3. Honestly

Part of Speech: Adverb
Meaning: In a truthful, straightforward way.
Best Used For: Expressing candid feeling or opinion.
Example: “Honestly, I sincerely didn’t expect that outcome.”
Nuance: Leans slightly more toward truthfulness than warmth compared to sincerely.
Synonym Strength: Close

4. Wholeheartedly

Part of Speech: Adverb
Meaning: With complete sincerity and enthusiasm.
Best Used For: Strong emotional statements or endorsements.
Example: “I wholeheartedly support your decision.”
Nuance: More intense and enthusiastic than sincerely.
Synonym Strength: Close

5. Earnestly

Part of Speech: Adverb
Meaning: With serious and heartfelt intent.
Best Used For: Requests, pleas, or serious statements.
Example: “I earnestly ask for your understanding.”
Nuance: Sounds slightly more formal and old-fashioned than sincerely.
Synonym Strength: Close

6. Heartily

Part of Speech: Adverb
Meaning: With warmth and full feeling.
Best Used For: Enthusiastic agreement or congratulations.
Example: “I heartily congratulate you on the achievement.”
Nuance: Warmer and more enthusiastic in tone than sincerely.
Synonym Strength: Contextual

7. Truthfully

Part of Speech: Adverb
Meaning: In accordance with the truth.
Best Used For: Emphasizing accuracy of a statement.
Example: “Truthfully, I sincerely think we should reconsider.”
Nuance: Focuses on factual accuracy rather than emotional genuineness.
Synonym Strength: Contextual

8. From the Heart

Part of Speech: Idiomatic phrase
Meaning: Expressed with genuine emotion.
Best Used For: Personal, emotional writing.
Example: “She spoke from the heart at the memorial.”
Nuance: More vivid and emotional than the plain adverb sincerely.
Synonym Strength: Contextual, idiomatic

9. In Earnest

Part of Speech: Idiomatic phrase
Meaning: With serious, genuine intent.
Best Used For: Formal or slightly old-fashioned writing.
Example: “He spoke in earnest about his concerns.”
Nuance: More formal and less common in casual speech than sincerely.
Synonym Strength: Contextual, idiomatic

10. Unreservedly

Part of Speech: Adverb
Meaning: Completely, without holding anything back.
Best Used For: Strong formal statements, especially apologies.
Example: “I unreservedly apologize for the delay.”
Nuance: Stronger and more absolute than sincerely.
Synonym Strength: Close (stronger)

11. Best Regards

Part of Speech: Closing phrase
Meaning: A polite, standard way to close a letter or email.
Best Used For: Everyday professional correspondence.
Example: “Best regards, Michael.”
Nuance: The most common neutral professional closing; less personal than sincerely can feel.
Synonym Strength: Very Close (closing sense)

12. Kind Regards

Part of Speech: Closing phrase
Meaning: A courteous, slightly warmer closing than “Best regards.”
Best Used For: Professional emails with a friendlier tone.
Example: “Kind regards, Sarah.”
Nuance: A touch warmer than “Best regards,” still professional.
Synonym Strength: Close (closing sense)

13. Warm Regards

Part of Speech: Closing phrase
Meaning: A friendly, personable closing.
Best Used For: Semi-formal or personal-professional correspondence.
Example: “Warm regards, Aunt Linda.”
Nuance: Noticeably friendlier than a standard business closing.
Synonym Strength: Close (closing sense)

14. Yours Truly

Part of Speech: Closing phrase
Meaning: A traditional, slightly formal closing.
Best Used For: American formal or semi-formal letters.
Example: “Yours truly, Robert Ellis.”
Nuance: Slightly old-fashioned compared to “Sincerely,” but functionally similar.
Synonym Strength: Very Close (closing sense)

15. Yours Faithfully

Part of Speech: Closing phrase
Meaning: A formal British closing used when the recipient’s name is unknown.
Best Used For: Formal British correspondence addressed to “Dear Sir/Madam.”
Example: “Yours faithfully, [Signature].”
Nuance: Governed by a specific British convention; incorrect if the recipient’s name is known and used in the greeting.
Synonym Strength: Close (formal, British convention)

16. Respectfully

Part of Speech: Closing phrase / adverb
Meaning: With deference and respect, especially toward someone of higher authority.
Best Used For: Formal, hierarchical, or legal correspondence.
Example: “Respectfully, Officer Daniels.”
Nuance: Implies deference rather than warmth or personal sincerity.
Synonym Strength: Contextual

17. Cordially

Part of Speech: Closing phrase / adverb
Meaning: In a polite, friendly, but somewhat formal manner.
Best Used For: Business correspondence that wants to sound polished.
Example: “Cordially, The Events Committee.”
Nuance: Polite but can feel a bit distant or stiff compared to sincerely.
Synonym Strength: Contextual

18. Warmly

Part of Speech: Closing phrase / adverb
Meaning: In a friendly, affectionate manner.
Best Used For: Personal letters or friendly professional relationships.
Example: “Warmly, Priya.”
Nuance: More overtly friendly than sincerely, less formal.
Synonym Strength: Close (closing sense)

19. Best Wishes

Part of Speech: Closing phrase
Meaning: A warm, general closing expressing goodwill.
Best Used For: Semi-formal letters, especially around events or milestones.
Example: “Best wishes, The Whole Team.”
Nuance: Warmer and more celebratory than a plain business sign-off.
Synonym Strength: Close (closing sense)

20. Take Care

Part of Speech: Closing phrase (informal)
Meaning: A casual, caring way to end a message.
Best Used For: Informal emails between colleagues or friends.
Example: “Take care, Jordan.”
Nuance: Too casual for formal business correspondence.
Synonym Strength: Contextual, informal

Additional Alternatives and Related Terms

More Formal and Semi-Formal Closings

• Faithfully — a shortened, slightly less common version of “Yours faithfully.”
• With appreciation — closes on a note of gratitude.
• With gratitude — similar to “With appreciation,” slightly more heartfelt.
• All the best — a friendly, general-purpose closing.
• Regards — the shortest and most neutral of the “regards” family.
• With respect — similar to “Respectfully,” slightly softer.
• Yours respectfully — a more formal variant combining “yours” with respect.
• Yours in service — used in some professional or civic contexts.

More Adverb Alternatives for Genuine Feeling

• Deeply — adds emotional intensity (“I deeply regret the misunderstanding”).
• Really — a casual, general-purpose intensifier; too informal for most professional writing.
• Whole-heartedly — an alternate spelling of “wholeheartedly.”
• With all my heart — a vivid, emotional idiom.
• Unfeignedly — a rare, formal word meaning without pretense; largely archaic today.

Informal Closings

• Cheers — common in British and Australian informal correspondence.
• Thanks — a practical, informal closing focused on gratitude rather than sincerity.
• Talk soon — casual, personal closing implying future contact.

Closest, Contextual, and Related Alternatives

Formal and Informal Alternatives

Formal/adverb: unreservedly, earnestly, in earnest, truthfully.

Formal/closing: Yours faithfully, Respectfully, Cordially.

Neutral/everyday: genuinely, truly, honestly, Best regards, Kind regards.

Informal/closing: Take care, Thanks, Cheers.

Sincerely vs Similar Words

Sincerely vs Best Regards

Both are common professional email closings, but “Sincerely” tends to feel slightly more personal or weighty, often used in formal letters, cover letters, and complaints. “Best regards” is more neutral and common for routine professional emails.

Sincerely vs Respectfully

“Respectfully” implies deference, often used when writing to someone in a position of authority. “Sincerely” doesn’t carry that same implication of hierarchy.

Sincerely vs Genuinely

As adverbs, they’re very close, but “genuinely” sounds more natural in casual speech, while “sincerely” leans slightly more formal, especially in written apologies and requests.

Sincerely vs Yours Faithfully

“Yours faithfully” follows a specific British rule: it’s used only when the letter opens with “Dear Sir/Madam” rather than a named recipient. “Sincerely” (or “Yours sincerely” in British usage) is used when the recipient’s name is known.

Words Related to Sincerely That Are Not Exact Synonyms

• Respectfully — focuses on deference and hierarchy, not warmth or genuineness.
• Cordially — polite but can sound formal and slightly distant.
• Really — a general-purpose intensifier, far too casual for most formal contexts.
• Faithfully — governed by a specific rule about unknown recipients; incorrect if misapplied.
• Frankly — implies bluntness or directness, not necessarily warmth or genuine feeling.

Words Related to Sincerely

Related vocabulary that broadens the topic without being direct synonyms: correspondence, valediction, salutation, tone, formality, closing line, signature.

Common Collocations With Sincerely

• sincerely hope
• sincerely believe
• sincerely apologize
• sincerely appreciate
• sincerely regret
• sincerely yours

Antonyms of Sincerely

• Insincerely — the direct grammatical opposite, meaning without genuine feeling.
• Falsely — implies deliberate deception rather than genuine intent.
• Disingenuously — implies a misleading appearance of sincerity that isn’t real.
• Half-heartedly — implies weak or incomplete commitment, the opposite of wholehearted sincerity.

How to Choose the Right Synonym for Sincerely

Start by identifying whether you’re modifying a verb mid-sentence or closing a letter.

For mid-sentence emphasis, “genuinely,” “truly,” or “wholeheartedly” all read naturally. Example: “I sincerely regret the mistake” and “I truly regret the mistake” are close to interchangeable.

For a letter or email closing, match the formality of the message: use “Yours faithfully” only for unnamed recipients in British correspondence, “Best regards” or “Kind regards” for everyday professional emails, and “Warmly” or “Best wishes” when a bit more warmth is appropriate.

Avoid using “Respectfully” as a casual substitute for “Sincerely,” since it implies a specific power dynamic that most everyday correspondence doesn’t need.

Common Mistakes When Using Sincerely Synonyms

• Using “Yours faithfully” with a named recipient. In British convention, it’s reserved for unknown recipients only.
• Treating “Respectfully” as interchangeable with “Sincerely.” It implies deference, not just genuine feeling.
• Using “Really” in formal writing. It’s far too casual for professional letters or documents.
• Mixing adverb-sense synonyms into closings. “Genuinely,” works as a mid-sentence adverb but sounds odd standing alone as a letter closing.

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Frequently Asked Questions

What Is Another Word for Sincerely?

As an adverb, “genuinely” or “truly” work well. As a letter closing, “Best regards” or “Yours truly” are common alternatives.

What Is a Formal Synonym for Sincerely?

“Yours faithfully” and “Respectfully” are common formal closings, while “unreservedly” works as a formal adverb.

What Is an Informal Synonym for Sincerely?

“Take care,” “Thanks,” and “Cheers” are common informal closings; “really” works as a casual adverb substitute.

What Is the Difference Between Sincerely and Yours Faithfully?

“Yours faithfully” is a specifically British closing used only when the recipient’s name is unknown, while “Sincerely” (or “Yours sincerely” in British usage) is used when the name is known.

Is Respectfully the Same as Sincerely?

No. “Respectfully” implies deference toward someone in authority, while “Sincerely” simply signals genuine, honest intent without implying hierarchy.

What Is the Opposite of Sincerely?

“Insincerely” is the direct opposite, along with related words like “falsely” and “disingenuously.”

What Is the Noun Form of Sincerely?

Sincerity is the standard noun form, referring to the quality of being genuine and honest.

Is Sincerely Formal or Informal?

Sincerely sits in a neutral-to-formal register; it works in professional letters and personal writing but sounds slightly out of place in very casual conversation.

Conclusion

Sincerely splits into two jobs that need different substitutes: as an adverb, genuinely, truly, and wholeheartedly capture its meaning inside a sentence, while Best regards, Yours faithfully, and Warmly cover the letter-closing sense depending on formality. Respectfully and Cordially are close in tone but carry their own implications of deference or distance, and Really is simply too casual for the contexts where sincerely usually appears. Choosing well comes down to recognizing which of sincerely’s two roles you’re actually replacing.