(initial capital letter) Classical Mythology. a mountain nymph who pined away for love of the beautiful youth narcissus until only her voice remained.
8.
Cards. the play of a high card and then a low card in the suit led by one's partner as a signal to continue leading the suit, as in bridge, or to lead a trump, as in whist.
9.
Electronics. the reflection of a radio wave, as in radar or the like.
10.
(initial capital letter) U.S. Aerospace. one of an early series of inflatable passive communications satellites.
11.
a word used in communications to represent the letter E.
A repeated sound that is caused by the reflection of sound waves from a surface. The sound is heard more than once because of the time difference between the initial production of the sound waves and their return from the reflecting surface.
A wave that carries a signal and is reflected. Echoes of radio signals (carried by electromagnetic waves) are used in radar to detect the location or velocity of distant objects.