after a negative statement used as an intensive meaning something like `likewise' or `also'; "he isn't stupid, but he isn't exactly a genius either"; "I don't know either"; "if you don't order dessert I won't either"
Other; one or something beside; as, Who else is coming? What else shall I give? Do you expect anything else?
Upon any less condition than (the fact or thing stated in the sentence or clause which follows); if not; supposing that not; if it be not; were it not that; except; as, we shall fail unless we are industrious.