kar·at noun orcar·at\ˈkarət also ˈker-\ (-s) Etymology: probably from Middle French carat, from Medieval Latin carratus unit of weight for precious stones — more at carat : a unit of fineness for gold equal to 1/24 part of pure gold in an alloy < 16-karat gold contains 16/24 pure gold > < 24-karat gold is pure > — abbr. k or kt