echo

Echo describes a sound repeating by sound wave reflection, having a lasting or far reaching impact, or repeating what someone else has said. (verb)

An example of echo is the repeating of a sound created by footsteps in an empty marble hallway.
An example of echo is a new social program having a far reaching and lasting impact on society.
An example of echo is a teacher agreeing with and repeatiung what a parent says.

An echo is a sound that is repeating after the original sound ended. (noun)

An example of an echo is the sound that comes back to you as a repeat of your own shout.

See echo in Webster's New World College Dictionary