thorny adj.

Old English þorn "sharp point on a stem or branch," earlier "thorny tree or plant," from Proto-Germanic *thurnīn- (source also of Old Saxon, Old Frisian thorn, Dutch doorn, Old High German dorn, German Dorn, Old Norse þorn, Gothic þaurnus), from PIE *trnus (source also of Old Church Slavonic trunu "thorn," Sanskrit trnam "blade of grass," Greek ternax "stalk of the cactus," Irish trainin "blade of grass"), from *(s)ter-n- "thorny plant," perhaps from root *ster- (1) "stiff."

Figurative sense of "anything which causes pain" is recorded from early 13c. (thorn in the flesh is from II Corinthians xii.7). Also an Anglo-Saxon and Icelandic runic letter (þ), named for the word of which it was the initial (see th).

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.