BADGE

A mark, sign, token, or thing, says Webster, by which a person is distinguished in a particular place or employment, and designating his relation to a person or to a particular occupation. It is in heraldry the same thing as a cognizance, a distinctive mark or badge. Thus, the followers and retainers of the house of Percy wore a silver crescent as a badge of their connection with that family; a representation of the white lion borne on the left arm was the badge of the house of Howard, Earl of Surrey ; the red rose that of the House of Lancaster, and the white rose, of York.

So the apron, formed of white lambskin, is worn by the Freemason as a badge of his profession and a token of his connection with the Fraternity (see A pron).