1600, "at leisure, not occupied," from un- (1) "not" + past participle of employ. Meaning "temporarily out of work" is from 1660s. The noun meaning "unemployed persons collectively" is from 1782; unemployment first recorded 1888.
[Say the] voices of the unemployed ...
No man has hired us
With pocketed hands
And lowered faces
We stand about in open places
And shiver in unlit rooms ...