Yours, Etc.: Origins and Uses of 8 Sign-Offs
late 14c., "place for washing;" mid-15c. "act of washing," from Old French lavanderie, from Latin lavandaria, plural of lavandarium "things to be washed," from lavare "to wash" (see lave). As a verb, from 1880. Laundry list in figurative sense is from 1958.
[second sense from the fact that some cadets were washed out, ''failed,'' by such a board]