"of or pertaining to the Moors," mid-15c., moreis, morys, morreys, from Moor + -ish. Earlier was Moreske (mid-14c.), from Old French moresque, morisque. Also compare Morisco, Moresco.
Entries linking to moorish
moor v.
"to fasten (a ship) in a particular location by or as by cables, anchors, etc.," late 15c., probably related to Old English mærels "mooring rope," via unrecorded *mærian "to moor," or possibly borrowed from Middle Low German moren or Middle Dutch maren "to moor," from West Germanic *mairojan. Related: Moored, mooring. French amarrer is from Dutch.
-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.