marker

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. One that marks or serves as a mark, as:
2. n. A bookmark.
3. n. A tombstone.
4. n. A milestone.
5. n. An implement, especially a felt-tipped pen, used for marking or writing.
6. n. One who marks objects, especially for industrial purposes.
7. n. One who grades student papers.
8. n. Sports A device, such as a line, stake, or flag, set on a playing field and showing the playing or scoring position.
9. n. Sports A player who guards an opponent, as in soccer.
10. n. Sports An official in certain court games, such as squash, who mainly judges whether the ball is out of play and whether a fault or let has occurred.
11. n. Games One that keeps score in various games.
12. n. Games A score in a game.
13. n. Slang A written, signed promissory note.
14. n. A genetic marker.
15. n. Medicine A physiological substance, such as human chorionic gonadotropin or alpha-fetoprotein, that when present in abnormal amounts in the serum may indicate the presence of disease, as that caused by a malignancy. Also called biomarker.
16. n. Linguistics An element that indicates grammatical class or function; a derivational or inflectional morpheme.

Century Dictionary and Cyclopedia

1. n. One who or that which marks. Specifically— One who marks the score at games.
2. n. A counter used in card-playing.
3. n. One who marks or notices; a close observer; hence, rarely, a marksman.
4. 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. It may be, for instance, a marking-plow, a form of three-tined harrow, or a removable attachment to a planter or plow.
5. 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.
6. n. A pen or stylus used for marking or recording.
7. n. Specifically, a counter (an oblong piece of bone) used in faro. One marker is placed on a player's bet, and another on a card so far removed from it that he cannot take in both bets by any of the usual ways of placing bets on the lay-out. From the fact that the marker is not a chip, and has no value except to point out the superior value elsewhere, arose the colloquial expression: “he is not a marker to so-and-so.”
8. 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.
9. 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.

Wiktionary

1. n. An object used to mark a location.
2. n. Someone or something that marks.
3. n. A felt-tipped pen.
4. n. slang A signed note of a debt to be paid.
5. n. slang, figuratively A nonmonetary debt owed to someone, especially in return for a favor.
6. n. paintball A device that fires a paintball
7. n. sports A defending player who stays close to an opponent in order to mark them.
8. v. To mark or write on (something) using a marker

GNU Webster's 1913

1. n. One who keeps account of a game played, as of billiards.
2. n. A counter used in card playing and other games.
3. n. (Mil.) The soldier who forms the pilot of a wheeling column, or marks the direction of an alignment.
4. n. An attachment to a sewing machine for marking a line on the fabric by creasing it.

WordNet 3.0

1. n. a writing implement for making a mark
2. n. some conspicuous object used to distinguish or mark something
3. n. a distinguishing symbol