1. A barrier constructed across a waterway to control the flow or raise the level of water.
2. A body of water controlled by such a barrier.
3. A barrier against the passage of liquid or loose material, as a rubber sheet used in dentistry to isolate one or more teeth from the rest of the mouth.
4. an obstruction; a hindrance.
5. to hold back or confine by means of a dam.
6. to close up; obstruct: he tried to dam his grief. see synonyms at hinder1.
7. A female parent. used of a four-legged animal.
8. archaic A mother.
9. decameter

1. symbol for the decameter (decametre), an si unit of length equal to 101 meters (metres).
2. structure placed across a flowing body of water to stop the flow.
3. A device to prevent a tooth from getting wet, consisting of a rubber sheet held with a band.
4. A reservoir.
5. to block the flow of water.
6. female parent, mother, generally regarding breeding of animals (correlative to sire).

1. A female parent; -- used of beasts, especially of quadrupeds; sometimes applied in contempt to a human mother.
2. A king or crowned piece in the game of draughts.
3. A barrier to prevent the flow of a liquid; esp., a bank of earth, or wall of any kind, as of masonry or wood, built across a water course, to confine and keep back flowing water.
4. A firebrick wall, or a stone, which forms the front of the hearth of a blast furnace.
5. to obstruct or restrain the flow of, by a dam; to confine by constructing a dam, as a stream of water; -- generally used with in or up.
6. to shut up; to stop up; to close; to restrain.

1. to obstruct or restrain the flow of by a dam; confine or raise the level of by constructing a dam, as a stream of water: often with in, up.
2. to confine or restrain as if with a dam; stop or shut up or in; obstruct: with up.
3. A mole, bank, or mound of earth, or a wall, or a frame of wood, constructed across a stream of water to obstruct its flow and thus raise its level, in order to make it available as a motive power, as for driving a mill-wheel; such an obstruction built for any purpose, as to form a reservoir, to protect a tract of land from overflow, etc.; in law, an artificial boundary or means of confinement of running water, or of water which would otherwise flow away.
4. in mining, any underground wall or stopping, constructed of masonry, clay, or timber, for the purpose of holding back water, air, or gas.
5. in dentistry, a guard of soft rubber placed round a tooth to keep it free from saliva while being prepared for filling.
6. the body of water confined by a dam.
7. A female parent: used of beasts, particularly of quadrupeds, and sometimes (now usually in a slighting sense) of women.
8. A crowned man in the game of draughts or checkers.
9. A fire-brick wall forming the front of the hearth or crucible of a blast-furnace, through which the tap-hole is formed.

1. a barrier constructed to contain the flow of water or to keep out the sea
2. obstruct with, or as if with, a dam
3. a metric unit of length equal to ten meters
4. female parent of an animal especially domestic livestock