n.
Pronunciation: im- ' p ē -d ə n(t)s
Function: noun
Date: 1886
: something that impedes : HINDRANCE : as a : the apparent opposition in an electrical circuit to the flow of an alternating current that is analogous to the actual electrical resistance to a direct current and that is the ratio of effective electromotive force to the effective current b : the ratio of the pressure to the volume displacement at a given surface in a sound-transmitting medium