泯 is a bound classical character — almost never standalone. You'll meet it in fixed phrases like
良心未泯 (liángxīn wèi mǐn — 'conscience not yet extinguished') and
童心未泯 (tóngxīn wèi mǐn — 'still has a child's heart'), and in compounds
泯灭 (mǐnmiè — to be obliterated) and
泯没 (mǐnmò — to vanish).
