Slim  —adj. (slimmer, slimmest) 1 not fat, slender. 2 small, insufficient (slim chance). —v. (-mm-) (often foll. By down) 1 become slimmer by dieting, exercise, etc. 2 make smaller (slimmed it down to 40 pages).  slimmer n. Slimming n. & adj. Slimmish adj. [low german or dutch]