(derogatory) To live together, especially of an unmarried couple.

(transitive) To fasten with a button or buttons. / (intransitive) To fasten all the buttons on a coat, or similar item of clothing, to keep warm.

(transitive, idiomatic) To fasten (a piece of clothing, etc.); to tighten (a nut etc.)

To close with a zip fastener. / (idiomatic, transitive or intransitive) To close as if with a zip fastener. / To convert a computer file into a smaller package.

To leave abruptly.

(Britain, informal) To pay for something, often with reluctance.

(transitive) To put into a couple; to put into, or connect together as, a group of two. / (intransitive) To get into pairs; to become a group of two.

simple past tense and past participle of shack up

Sharing a small room or accommodation between many (often too many) people / (idiomatic) (of a couple) Sharing a house, but not married.

(directed at a horse) move on!, go faster!