Probably from Proto-Indo-European *kelh₁- (“to shout”), which is imitative. Cognates Related to Old English hlowan (“to low, make a noise like a cow”), Old High German halan (“to call”), Ancient Greek κλεδον (kledon, “report, fame”), κλήση (klḗsē, “to call”), κέλαδος (kélados, “noise”), Middle Irish cailech (“cock”), Latin calō (“to call out, announce solemnly”), Sanskrit उषःकल (uṣaḥkala, “cock”, literally “dawn-calling”).