wiktionary
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From Swede + -ish. Cognate with Dutch Zweeds, German Schwedisch.
etymonline
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Swedish (adj.)
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.
