slim. adjective slimmer or slimmest. small in width relative to height or length. small in amount or qualityslim chances of success verb slims, slimming or slimmed. Synonyms for slimmer at Thesaurus.com with free online thesaurus, antonyms, and definitions. Find descriptive alternatives for slimmer. slimmer meaning: a person who is trying to get thinner by eating less and doing more exercise. Learn more. Definition of slimmer. chiefly British. : a person dieting to lose weight. Person that starts going to the gym to lose an unspecified amount of weight and has no fitness goals beyond looking better in the mirror. This person generally . slimmer (plural slimmers) A person who is trying to become slim by dieting. Adjective: slim (slimmer,slimmest) slim. Being of delicate or thin build 'a slim girl with straight blonde hair'; - slender, slight, svelte · Small in quantity 'a slim . Instantly create a smoother shape with a Body Slimmer. Find a Plus Size Body Slimmer, Mother of the Bride Body Slimmer and others available at Macy's. Amazon.com: Functional Silicone Rubber Face Facial Slimmer Exercise Mouthpiece Anti Wrinkle by Abcstore99: Sports & Outdoors.