1) Affectionately 2) Earnestly 3) Ex animo 4) Frankly 5) In earnest 6) In good faith 7) Intensely 8) Modestly 9) Truly 10) Truthfully 11) Unaffectedly 12) Unfeignedly 1) Closing remark 2) Gravely 3) Industriously 4) Intently 5) Seriously 6) Solemnly 7) Truly 8) Unfeignedly 9) With honesty 10) With sincerity 11) Without hypocrisy 12) Without pretense 
• (adv.) Honestly; unfeignedly; without dissimulation; as, to speak one`s mind sincerely; to love virtue sincerely. • (adv.) Purely; without alloy. • (adv.) In a sincere manner.
Sin·cere'ly adverb In a sincere manner. Specifically: (a) Purely; without alloy. Milton. (b) Honestly; unfeignedly; without dissimulation; as, to speak one's mind sincerely ; to love virtue sincerely . 
[adv] - with sincerity 2. [adv] - written formula for ending a letter
sincerely 1. In an honest and unaffected way: 'She sincerely told her parents everything that was in her feelings.' 2. A written formula for ending a letter; such as, 'Yours sincerely' is often used immediately before the signature at the end a letter or e-mail, which is addressed to somebody by name; another example, 'Sincerely yours, Jim Mason'....
adverb written formula for ending a letterunfeignedly adverb 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`