Insincere
Insincere , adjective
[Latin insincerus. See In- not, and Sincere.]
1.
Not being in truth what one appears to be; not sincere; dissembling; hypocritical; disingenuous; deceitful; false; -- said of persons; also of speech, thought; etc.; as, insincere declarations.
2.
Disappointing; imperfect; unsound. [Obsolete]
To render sleep's soft blessings insincere.