From Longman Dictionary of Contemporary Englishsinceresin‧cere /sɪnˈsɪə $ -ˈsɪr/ ●○○ adjective 1 REAL/NOT FALSE OR ARTIFICIALa feeling, belief, or statement that is sincere is honest and true, and based on what you really feel and believe SYN genuinesincere thanks/thank you/gratitude I would like to say a sincere thank you to everyone who has helped and supported me. Please accept my sincere apologies. his sincere desire to find out the truth2 HONESTsomeone who is sincere is honest and says what they really feel or believe OPP insincere a warm-hearted, sincere mansincere in They were obviously sincere in their beliefs. I wasn’t sure that he was sincere in what he was saying.
Examples from the Corpussincere• My smile is not entirely sincere.• She said she would love to come, but I wasn't sure if she was being sincere.• If Annan is sincere about reform, he should set an example by taking a pay cut.• He also struck me as wholly sincere and a very decent sort.• My client extends his sincere apologies to anyone who may have been hurt by his actions.• I would like to express my sincere appreciation for your hard work.• It is my sincere belief that if we work together we can achieve peace in this country.• Over the years, he has made a sincere effort to improve race relations.• There is no doubt that they were sincere in their belief that their patients would benefit from their involvement.• They seemed to be sincere in their concern for the children's welfare.• To the jury, I was just that young country lawyer, that sincere kid representing a poor client.• But his condemnation of gay rights was likely made with all sincere passion.• She's a hardworking, sincere person.• I would like to express my sincere thanks to all those who helped us.sincere apologies• To any readers who feel hard done by or annoyed please accept my sincere apologies.• Firstly, my sincere apologies for not having contacted you earlier about your proposal.sincere in• They were completely sincere in their beliefs.Origin sincere (1500-1600) Latin sincerus “clean, pure”