(1):

(superl.) Honest; free from hypocrisy or dissimulation; as, a sincere friend; a sincere person.

(2):

(superl.) Being in reality what it appears to be; having a character which corresponds with the appearance; not falsely assumed; genuine; true; real; as, a sincere desire for knowledge; a sincere contempt for meanness.

(3):

(superl.) Pure; unmixed; unadulterated.

(4):

(superl.) Whole; perfect; unhurt; uninjured.