slacks

noun

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.)
“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!”
“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.”