Honestly; unfeignedly; without dissimulation; as, to speak one's mind sincerely; to love virtue sincerely.

with sincerity; without pretense; "she praised him sincerely for his victory"; "was unfeignedly glad to see his old teacher"; "we are truly sorry for the inconvenience"

written formula for ending a letter

"Sincerely" is a popular song written by Harvey Fuqua and Alan Freed and published in 1954.

Purely; without alloy.

In a sincere manner.