Etymology
Advertisement
-ish 
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.
Related entries & more 
Advertisement
dimmish (adj.)

"rather dim," 1680s, from dim (adj.) + -ish.

Related entries & more 
Advertisement
purplish (adj.)

"somewhat purple," 1560s, from purple (n.) + -ish.

Related entries & more 
pinkish (adj.)

"somewhat pink," 1784, from pink (n.) + -ish.

Related entries & more 
faddish (adj.)
1855, from fad + -ish. Related: Faddishness.
Related entries & more 
blackish (adj.)
"somewhat black, moderately dark," mid-15c., from black (adj.) + -ish.
Related entries & more