Unsincere is a term used to describe people who are deceptive, dishonest, or insincere. It is often seen as negative and untrustworthy. Some synonyms for unsincere include disingenuous, insincere, false, deceitful, dishonest, and fake. These words all suggest that someone is pretending to be something they are not and are not being truthful or sincere in their actions or words. Other synonyms include untruthful, hypocritical, duplicitous, and two-faced. In contrast, synonyms for sincere include genuine, authentic, honest, truthful, and heartfelt. These words suggest that someone is being true to themselves and others and is expressing genuine feelings.