slimy (adj.)

"Any soft, ropy, glutinous, or viscous substance" [Century Dictionary], Old English slim "soft mud," from Proto-Germanic *slimaz (source also of Old Norse slim, Old Frisian slym, Dutch slijm "slime, phlegm," German Schleim "slime"), which is probably related to Old English lim "birdlime; sticky substance."

This is from a PIE root *(s)lei- "slimy, sticky, slippery" (source also of Sanskrit linati "sticks, stays, adheres to; slips into, disappears;" Russian slimak "snail;" Old Church Slavonic slina "spittle;" Old Irish sligim "to smear," leinam "I follow," literally "I stick to;" Welsh llyfn "smooth;" Greek leimax "snail," limne "marsh, pool, lake," alinein "to anoint, besmear;" Latin limus "slime, mud, mire," linere "to daub, besmear, rub out, erase").

As an insult to a person from mid-15c. Figuratively, of anything clinging and offensive, 1570s. Slime-mold, common name for a type of fungi, is from 1880.

adjective suffix, "full of or characterized by," from Old English -ig, from Proto-Germanic *-iga- (source also of Dutch, Danish, German -ig, Gothic -egs), from PIE -(i)ko-, adjectival suffix, cognate with elements in Greek -ikos, Latin -icus (see -ic). Originally added to nouns in Old English; used from 13c. with verbs, and by 15c. even with other adjectives (for example crispy). Adjectives such as hugy, vasty are artificial words that exist for the sake of poetical metrics.