"somewhat shrewd," by 1807; see shrewd + -ish. In some cases perhaps an error for shrewish.
Entries linking to shrewdish
shrewd adj.
c. 1300, shreued, "wicked, depraved, malicious, evil," from shrewe "wicked man" (see shrew) + -ed. Compare crabbed from crab (n.), dogged from dog (n.), wicked from witch (n.), all from early Middle English.
The weaker or neutral sense of "cunning, sly, artful, clever or keen-witted in practical affairs," hence "acute, sagacious" is recorded from 1510s. Related: Shrewdly; shrewdness. Strutt's "Sports and Pastimes of the People of England" (1801) and a mid-15th century list of terms of association have a shrewdness of apes for a company or group of them. Shrewdie "cunning person" is by 1916.
-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.