1878, Amer.Eng. and Canadian Eng., of unknown origin, perhaps from Mex.Sp. jacal,
from Nahuatl xacalli
"wooden hut." Or perhaps a back-formation from dial. Eng. shackly
"shaky, rickety" (1843), a derivative of shack
, a dial. variant of shake
(q.v.). Another theory derives shack
. Slang verb phrase shack up
"cohabit" first recorded 1935 (in Zora Neale Hurston).