Slimy means unpleasantly wet and slippery. Slimy stones, a slimy layer, slimy to the touch.
Slime is the substance, and it is produced by slugs, fish, algae and a great many other living things for perfectly good reasons. Of a person, slimy means insincerely charming in a way that makes your skin crawl — a slimy salesman — and it is among the more contemptuous descriptions available. Note slime mould, which is neither an animal nor a plant nor a fungus and is genuinely remarkable.
1adjectiveslimyUnpleasantly wet and slippery.
“The rocks at the edge of the river were green and slimy.”
2adjectiveinsincerelyInsincerely charming.
“The salesman was so slimy, full of compliments and fake smiles, that we left the shop.”
slimy is a quality of sliminess.
Old English slim is Germanic and related to Latin limus, mud, and to English lime. The word has meant the same sticky substance for a thousand years and has never once been complimentary.
Middle English
slymy
English, today
slimy
From Middle English slymy, slimi, either derived from the Old English - noun slīm or an unattested slīmiġ, replacing slipiġ. Equivalent to slime + -y. Cognate with Dutch slijmig, slijmerig (“slimy”), German schleimig (“slimy; smarmy”), Swedish slemmig (“slimy”).
Etymology from Wiktionary, CC BY-SA