Märk'er, n.
Sense 1. One who marks, affixes a sign, or takes notice.
Sense 2. One who, or that which, serves to indicate, keep account, or guide; especially, (a.) A counter used in card-playing. (b.) One who keeps account of a game played. (c.) (Mil.) The soldier who forms the pivot of a wheeling column, or marks the direction of an alignment.