n. One who or that which marks.n. A counter used in card-playing.n. One who marks or notices; a close observer; hence, rarely, a marksman.n. In agriculture, some implement used for tracing lines on the ground, as the position to be occupied by a row of plants or hills, or the like.n. In a sewing-machine, an attachment for making upon the cloth, as it passes the needle, a slight crease that may serve as a guide for folding a tuck, or for another line of stitching; a tuck-creaser.n. A pen or stylus used for marking or recording.n. n. Specifically, a counter (an oblong piece of bone) used in faro.n. At poker, any object placed upon the table to show that a player who has no chips is still in the pool: sometimes used in table-stakes to indicate that the player is supposed to have as much money in front of him as any other person at the table.n. In railroading, a flag, lamp, or other signal placed upon an engine or train, or upon an electric car, to indicate its character, destination, etc. The green flag at the end of a train is a marker, as is also a red tail-light, or an extra light upon a locomotive.