/ dæm; NAmE / noun , verb
■ noun
1.
a barrier that is built across a river in order to stop the water from flowing, used especially to make a reservoir (= a lake for storing water) or to produce electricity
2.
( technical ) the mother of some animals, especially horses
—compare sire
3.
= dental dam
■ verb
( -mm- ) [ vn ] dam sth (up) to build a dam across a river, especially in order to make an artificial lake for use as a water supply, etc.
••
WORD ORIGIN
noun sense 1 and verb Middle English : from Middle Low German or Middle Dutch ; related to Dutch dam and German Damm , also to Old English fordemman close up .
noun sense 2 late Middle English (denoting a human mother): alteration of dame .