providing for or allowing movement
in opposite directions, or both to and from a place: two-way traffic.
allowing or entailing communication or exchange between two persons, groups, countries, etc.
involving two parties or participants, as a relationship or agreement; two-sided: a two-way race for the nomination.
entailing responsibilities, obligations, etc., on both such parties.
capable of both receiving and sending signals: a two-way radio.
capable of being used in two ways.