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 from
ramshackle. Slang verb phrase
shack up "cohabit" first recorded 1935 (in Zora Neale Hurston).
[shak] 
