shackup

US: (shak′up′)

WordReference Random House Unabridged Dictionary of American English © 2025

shack•up  (shak′up′), n. [Slang.]

1. an instance of shacking up:
   The census people counted both marriages and shackups.

• noun, nominal use of verb, verbal phrase shack up 1945–50

WordReference Random House Learner's Dictionary of American English © 2025

shack¹ /ʃæk/   n. [countable]

1. a rough cabin;
   shanty.

v. [no object]

2. shack up, [no object* often: ~ + up + with + object] [Slang.] to live together or with another as sexual partners without being legally married.

WordReference Random House Unabridged Dictionary of American English © 2025

shack¹  (shak), n. 

1. a rough cabin;
   shanty.
2. [Informal.] See radio shack. 

v.i. 

3. shack up, [Slang.]
   • to live together as husband and wife without being legally married.
   • to have illicit sexual relations.
   • to live in a shack:
     He's shacked up in the mountains.

• compare earlier shackly rickety, probably akin to ramshackle (Mexican Spanish jacal "hut'' is a phonetically impossible source) 1875–80, American.

shack²  (shak), v.t. [Informal.]

1. Informal Terms to chase and throw back;
   to retrieve:
   to shack a ground ball.

• apparently special use of dialect, dialectal shack to shake 1825–35, American.

Collins Concise English Dictionary © HarperCollins Publishers::

shack up verb

1. (intr, adverb) usually followed by with: to live or take up residence, esp with a mistress or lover