c. 1600, from Swede + -ish. Similar formation in Dutch Zweedsch, German Schwedisch. Related: Swedishness. As a language name from c. 1600. The candy Swedish fish attested by that name by 1983.
Entries linking to swedish
Swede n.
"native of Sweden," 1610s, from Low German, from Middle Low German Swede, from a source akin to Old English Sweoðeod, literally "Swede-people," from Sweon (plural) "Swedes" (Old Norse, Old Swedish Sviar), called by the Romans Suiones, probably from Proto-Germanic *sweba "free, independent," or else from *geswion "kinsman."
-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.