What does “sincerely” mean?

Sincerely is an adverb meaning “genuinely” or “honestly.” It’s related to the adjective “sincere.” It’s commonly used on its own or in combination with “yours” as a sign-off at the end of an email message or letter. It’s a formal way of ending a message that emphasizes your honest intentions toward the recipient.

It’s also used in other contexts to emphasize the genuineness of a feeling (e.g., “I am sincerely sorry for my comments”).