Merriam-Webster Collegiate Dictionary - sincere

 adjective  (~r; ~st)  Etymology: Middle French, from Latin sincerus whole, pure, genuine, probably from sem- one + -cerus (akin to Latin crescere to grow) — more at same, crescent  Date: 1533  1.  a. free of dissimulation ; honest a ~ interest  b. free from adulteration ; pure a ~ doctrine ~ wine  2. marked by genuineness ; true  • ~ly adverb  • ~ness noun Synonyms:  ~, wholehearted, heartfelt, hearty, unfeigned mean genuine in feeling. ~ stresses absence of hypocrisy, feigning, or any falsifying embellishment or exaggeration a ~ apology. wholehearted suggests sincerity and earnest devotion without reservation or misgiving promised our wholehearted support. heartfelt suggests depth of genuine feeling outwardly expressed expresses our heartfelt gratitude. hearty suggests honesty, warmth, and exuberance in displaying feeling received a hearty welcome. unfeigned stresses spontaneity and absence of pretense her unfeigned delight at receiving the award.