The only free and comprehensive online etymological dictionary of the Spanish language
ciego m. (Adjective) "blind"
From Latin cæcus 'id.' From Proto-Italic *kaiko- 'id.' From Proto-Indo-European *keh2i-ko- "one-eyed."
Indo-European
Celtic
Old Irish cáech "one-eyed," Middle Breton coeg 'id.,' Old Cornish cuic 'id.'
Germanic
Gothic haihs "one-eyed"