Quiz: Remember the definition of mal de mer?
early 15c., from Middle French invincible (14c.) or directly from Latin invincibilis "unconquerable," from in- "not" (see in- (1)) + vincibilis "conquerable," from vincere "to overcome" (see victor). Related: Invincibly. Noun meaning "one who is invincible" is from 1630s. Invincible ignorance is from Church Latin ignorantia invincibilis (Aquinas). Related: Invincibly.