stylish adj.

early 14c., stile, "writing instrument, pen, stylus; piece of written discourse, a narrative, treatise;" also "characteristic rhetorical mode of an author, manner or mode of expression," and "way of life, manner, behavior, conduct," from Old French stile, estile "style, fashion, manner; a stake, pale," from Latin stilus "stake, instrument for writing, manner of writing, mode of expression," perhaps from the same source as stick (v.)). Spelling modified incorrectly by influence of Greek stylos "pillar," which probably is not directly related. As distinguished from substance, 1570s. Meaning "mode of dress" is from 1814.

adjectival word-forming element, Old English -isc "of the nativity or country of," in later use "of the nature or character of," from Proto-Germanic suffix *-iska- (cognates: Old Saxon -isk, Old Frisian -sk, Old Norse -iskr, Swedish and Danish -sk, Dutch -sch, Old High German -isc, German -isch, Gothic -isks), cognate with Greek diminutive suffix -iskos. In its oldest forms with altered stem vowel (French, Welsh). The Germanic suffix was borrowed into Italian and Spanish (-esco) and French (-esque). Colloquially attached to hours to denote approximation, 1916.

The -ish in verbs (abolish, establish, finish, punish, etc.) is a mere terminal relic from the Old French present participle.