Marker \Mark"er\, n. One who or that which marks. Specifically:
   (a) One who keeps account of a game played, as of billiards.
   (b) A counter used in card playing and other games.
   (c) (Mil.) The soldier who forms the pilot of a wheeling column, or marks the direction of an alignment.
   (d) An attachment to a sewing machine for marking a line on the fabric by creasing it.

Source: Webster's Revised Unabridged Dictionary (1913)