A barrier constructed across a waterway to control the flow or raise the level of water.
A body of water controlled by such a barrier.
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.
An obstruction; a hindrance.
To hold back or confine by means of a dam.
To close up; obstruct: He tried to dam his grief. See Synonyms at hinder1.