UNSINCE'RE, adjective 1. Not sincere; hypocritical. [See Insincere.] 2. Not genuine; adulterated. 3. Not sound; not solid. [Obsolete in the two last significations, and for the first, insincere is generally used.] INSINCERITY, noun Insincerity; cheat. [Not used.] [See Insincerity.]
Source: Webster's 1828 American Dictionary ↗ · public-domain · returned verbatim, no AI