blueblue

The story

From Middle English blew, blewe, from Anglo-Norman blew, from Middle French bleu, from Old French blöe, bleve, blef (‘blue’), from Frankish *blāu (‘blue’) (perhaps through a Late Latin blāvus, blāvius (‘blue’) attested from Isidore of Seville), from Proto-Germanic *blēwaz (‘blue, dark blue’), from Proto-Indo-European *bʰlēw- (‘yellow, blond, grey’). Possibly related also to English blee (‘colour’), from Old English blēo (‘colour’); but direct derivatives of Proto-Germanic *blēwaz (‘blue, dark blue’) in Old English include: Old English blāw and blēo (‘blue’), Old English blǣwen (‘bluish, light-blue’), blǣhǣwen (“blue-coloured, bluish, violet or purple colour”, literally “blue-hued”). There seems to be a parallel connection in Germanic between words for blue and colour, dually exemplified by Proto-West Germanic *blīu (‘colour, blee’) and *blāu (‘blue’); and Proto-Germanic *hiwją (‘colour, hue’) and *hāwī (‘blue, purple’). Also compare фиоле́тово (fiolétovo).

Full etymology on Wiktionary