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cantar (Verb) "to sing"
10th cent. From Latin cantare "to sing," "to chant." From Latin canare "to sing" and frequentive suffix -tare (see note under faltar for origin). From Proto-Italic *kan-e(je)- 'id.' From Proto-Indo-European *kh2n-e- 'id.'
Asturian cantar, Portuguese cantar, Galician cantar, Catalan cançó, French chanter, Italian cantare, Aromanian cãntu, Romanian cânta, Sardinian cantari
Old Irish canaid "sings," Welsh canu "to sing"
Gothic hana "cock," "rooster," Crimean Gothic ano 'id.,' Old Norse hani 'id.,' Old High German hano 'id.,' Old Saxon hano 'id.,' Old English hana 'id.'
Ancient Greek κᾰνᾰχέειν (kanakhéin) "to ring"
Sanskrit kaṇati "sing," Persian xândan 'id.'
Basque kantu "song," kantatu "to sing," borrowed from cantar

Originally canare meant "to sing" while cantare, with -tare added, was more forceful. Over time the impact of cantare was lost and began to match the meaning of canare. Thus, canare was replaced by cantare. When later speakers wanted to give force and frequency to the verb, they once again added -tare to cantare to form cantitare - unaware that their ancestors had created cantare from canare to fulfill that purpose. Cantitare has not survived in Spanish.

The Proto-Indo-European root behind cantar "prevailed only in Italic and Celtic, where it is associated with charms and spells as well as poetry. ...Latin cano, canto, cantus, carmen < *can-men, all of magical incantations as well as of singing in general." ~ M. West, Indo-European Poetry and Myth (2007)