Unable to exist if something else exists. Two things are incompossible when the world of being has scope enough for one of them, but not enough for both -- as Walt Whitman's poetry and God's mercy to man. Incompossibility, it will be seen, is only incompatibility let loose. Instead of such low language as "Go heel yourself -- I mean to kill you on sight," the words, "Sir, we are incompossible," would convey and equally significant intimation and in stately courtesy are altogether superior.
—Ambrose Bierce, The Devil's Dictionary