What is the term for a reflected sound wave?

The term "echo" specifically refers to a reflected sound wave that returns to the listener after bouncing off a surface such as a wall or mountain. When a sound wave travels, it can interact with surfaces in its environment. If the surface is solid and large enough relative to the wavelength of the sound, part of the sound wave will reflect back to the source or towards an observer, creating an echo. This phenomenon allows us to hear the original sound and its reflection as two distinct sound waves, given there is enough time between the original and reflected sounds for the human ear to perceive them separately.

Reverberation refers to a series of echoes that occur in a confined space, creating a prolonged sound, but does not define a single reflected sound wave. Reflection is a broader term that describes the bouncing of any wave, including sound, off a surface, but does not specify sound waves alone. Resonance involves the amplification of sound at specific frequencies and is not related to the concept of reflected sound. Hence, echo is the most precise term for what is being described in the question.