"somewhat brown," 1550s, from brown (adj.) + -ish.
Entries linking to brownish
brown adj.
Old English brun "dark, dusky," developing a definite color sense from 13c., from Proto-Germanic *brunaz (source also of Old Norse brunn, Danish brun, Old Frisian and Old High German brun, Dutch bruin, German braun), from PIE root *bher- (2) "bright; brown."
The Old English word also had a sense of "brightness, shining," preserved only in burnish. The Germanic word was adopted into Romanic (Middle Latin brunus, Italian and Spanish bruno, French brun).
Brown sugar is from 1704. Brown Bess, slang name for old British Army flintlock musket, is recorded by 1785. Brown study "state of mental abstraction or meditation" is from 1530s; OED says the notion is "gloomy." Brown-paper "kind of coarse, stout, unbleached paper used for wrapping" is from 1650s.
-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.