[syn: sincerely, sincerely yours]
The Collaborative International Dictionary of English v.0.48:
Sincerely \Sin*cere"ly\, adv.
   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.
       [1913 Webster]
WordNet (r) 3.0 (2006):
sincerely
    adv 1: 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" [syn: sincerely, unfeignedly, truly]
           [ant: insincerely]
    2: written formula for ending a letter [syn: sincerely,
       sincerely yours]