Definition of "slacks"

slacks

noun
1. plural of slack
noun
plural only, attributive slack
1. (dated) Semi-formal trousers which are less formal than those that are part of a suit but nowadays are considered suitable casualwear in most offices. (Takes a plural verb even when referring to a single pair; may be referred to as a pair of slacks.)
  Quotations
  Discipline, that’s what we need. Discipline. How are we going to win the war without discipline? Do you know, sir, some of these fellows come on parade in slacks - so I’ve been told. Can’t expect to win a war that way. Slacks! My God!
  1941, Agatha Christie, N or M?
  Not five minutes later, Zooey, with his hair combed wet, stood wet, stood barefoot at the washbowl, wearing a pair of beltless dark-gray sharkskin slacks, a face towel across his bare shoulders.
  1957, J. D. Salinger, “Zooey”, in Franny and Zooey, published 1961
verb
1. third-person singular simple present indicative of slack