to go forward, to advance, to go in, to enter, to put in, to submit, to take in, to admit, (math.) base of a number system, classifier for sections in a building or residential compound
to enter; to go into, to join; to become a member of, (bound form) to conform to (as in 入時|入时[ru4 shi2]), abbr. for 入聲|入声[ru4 sheng1], (on product packaging, after {number n} + {classifier}) containing (n pieces) (from Japanese 入 "iri")