Both.
Synonyms:
twain, two.
Both refers to two objects previously mentioned, or had in mind, viewed or acting in connection; as, both men fired at once; "two men fired" might mean any two, out of any number, and without reference to any previous thought or mention. Twain is a nearly obsolete form of two. The two, or the twain, is practically equivalent to both; both, however, expresses a closer unity. We would say both men rushed against the enemy; the two men flew at each other. Compare EVERY.
Antonyms:
each, either, every, neither, none, no one, not any.