昧 (w)

(mèi) conceal; dark

昧心 (w)

(mèixīn) against one's conscience

昧死 (w)

(mèisǐ) to risk one's life

昧没 (w)

(mèimò) veiled; obscure

昧良心 (w)

(mèiliángxīn) it goes against one's conscience