In'sin-cēre', a.

a. [Prefix in, not, and sincere; Fr. insincère, Lat. insincerus.]

1. Not being in truth what one appears to be; not sincere; dissembling; hypocritical, false;—said of persons; as, his professed friends were insincere.
2. Deceitful; hypocritical; false;—said of things; as, insincere declarations or professions.
3. Not to be trusted or relied upon; disappointing; imperfect; unsound. “To render sleep's soft blessings insincere.” Dryden.

Syn.—Dissembling; hollow; hypocritical; deceptive; deceitful; false; disingenuous.