Entry 1 sense Webster, 1913 Slatter /slăt'-ẽr/ · Slat·ter · IPA /slˈætər/ 01 v. i. To be careless, negligent, or aswkward, esp. with regard to dress and neatness; to be wasteful. 1. To be careless, negligent, or aswkward, esp. with regard to dress and neatness; to be wasteful.