MARKER

n. 1 a stone, post, etc., used to mark a position, place reached, etc. 2 a person or thing that marks. 3 a felt-tipped pen with a broad tip. 4 a person who records a score, esp. in billiards. 5 a flare etc. used to direct a pilot to a target. 6 a bookmark. 7 US sl. a promissory note; an IOU.