The crossword solutions for the term ECHO, E.G. are OREAD (5 letters), EFFECT (6 letters), and ANSWER (6 letters). An echo is a sound or voice that is repeated back to the original source. It is usually caused by sound waves bouncing off of a surface and returning to the original source. OREAD is a type of nymph in Greek mythology who lived in mountains and caves. The EFFECT of an echo is that it creates a reverberation or repetition of the original sound. An ANSWER is a response to a question or statement, and in the case of an echo, it is the sound that is repeated back to the original source.