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-ico Adjective-forming suffix

From Latin -icus 'id.' From Proto-Italic *-īko-. A decausative from the instrumental: Proto-Indo-European *-i̯h1-ko- 'id.'

Also an uncommon variant -eco reflects the i ~ e confusion in Vulgar Latin in Iberia.

Romance: Western Vulgar Latin: Asturian -icu, Portuguese -ico, Galician -ico, Catalan -ic, French -ique, Italian -ico; Eastern Vulgar Latin: Aromanian -ic; Extra-Comparanda: English -ic (borrowed from French -ique)

Indo-European: Balto-Slavic: Old Church Slavonic -ъkъ; Hellenic: Ancient Greek -ικός (ikós); Indo-Iranian: Sanskrit -śas