1. to enter; to go into
2. to join; to become a member of
3. (bound form) to conform to (as in 入時 rùshí)
4. abbr. for 入聲 rùshēng
5. (on product packaging, after {number n} + {classifier}) containing (n pieces) (from Japanese 入 "iri")

1. medicine
2. drug
3. substance used for a specific purpose (e.g. poisoning, explosion, fermenting)
4. to poison

classifiers: 種, 服, 味