The only free and comprehensive online etymological dictionary of the Spanish language
callar (Verb) "to silence"
12th cent. From Vulgar Latin *callare "to lower," from Latin calare 'id.,' from Greek χαλᾶν (khalan) 'id.' Of unknown origin.
Indo-European
Romance
Asturian callar, Portuguese calar, Galician calar, Catalan callar, Italian calare "to lower"