- A barrier constructed across a waterway to control the flow or raise the level of water. (noun)
- A body of water controlled by such a barrier. (noun)
- 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. (noun)
- An obstruction; a hindrance. (noun)
- To hold back or confine by means of a dam. (verb-transitive)
American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.