11th cent. From Latin natare 'id.,' from nare "to swim" with a frequentive suffix -tare (see note under faltar).
Latin nare is from Proto-Italic *(s)nā-je/o- 'id.' From Proto-Indo-European *sneh2-i̯e/o- 'id.,' from the root *sneh2- of the same meaning.
Romance: Western Vulgar Latin: Asturian nadar, Portuguese nadar, Galician nadar, Catalan nedar, Italian nuotare ; Eastern Vulgar Latin: Aromanian anot, Romanian înota ; Sardinian: anatare
Indo-European: Celtic: Old Irish snaïd "to swim," Middle Welsh nawf "swimming," Middle Breton neuff 'id.;' Hellenic: Ancient Greek νήχω (nékho) "I swim;" Indo-Iranian: Sanskrit snātas "he bathes," Young Avestan fra-snaiia- "to wash;" Tocharian: B nāsk- "to swim"