"having an offensive odor," 1854, from smell (n.) + -y (2). Related: Smelliness.
Entries linking to smelly
smell n.
c. 1200, smel, "scent as a property of matter, that quality of anything that may be perceived by the nose," also "pleasant odor; aromatic substance;" see smell (v.). Not found in Old English, where the usual word was stenc (see stench). Smell is attested specifically as "stench, offensive smell" by late 14c.
-y 2
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.