13th cent. From Latin latus 'id.'
From Proto-Italic *slāto- 'id.' Of disputed origin.
Also the origin of the surname Lado.
Romance: Western Vulgar Latin: Portuguese lato, Catalan lat, Italian lato ; Eastern Vulgar Latin: Aromanian lat, Romanian lat
Indo-European: Celtic: Old Irish con·slá? "to go away" (a connection held by de Vaan (2014), but has not convinced most authorities on semantic grounds - the semantic gap between 'going away' and 'side' is more of a cavernous abyss than a small hurdle); Balto-Slavic: Old Church Slavonic stьlati? "broaden" (classically linked to Latin latus, but now reconstructed in Proto-Indo-European without a laryngeal as *stel- "to place" (Rix, et al. 2001))