What is the emblem of the increasing moon with horns directed upward, when used in a coat of arms; -- often used as a mark of cadency to distinguish a second son and his descendants called?

crescent — (Her.) The emblem of the increasing moon with horns directed upward, when used in a coat of arms; -- often used as a mark of cadency to distinguish a second son and his descendants. (Webster's 1913.)

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