carat: [16] The carat gets its name from the use of carob beans as standard weights for measuring the heaviness of small quantities. The Greek name for the elongated seed pod of the carob tree was kerátion, a derivative of kéras ‘horn’ (related to English horn). This passed into Arabic as qīrāt, where it became formalized in a system of weights and measures as ‘four grains’. It passed into English via Italian carato and French carat. => horn
