I like to consider sound as the transmitted pattern of vibration of molecules through a medium (usually air, can be solid or liquid or any other gas too) that is received by a suitable sensor (e.g. our eardrum, middle ear bones, and inner ear auditory receptors - but can also be an artificial receptor like a microphone) and interpreted by a suitable processing centre (e.g. the main auditory cortex located in the brain's temporal lobes, or a sound card's processor) from which actions can be carried out based on that interpretation (e.g. we turn up the music that we appreciate, we react to an auditory hallucination of a voice that isn't there, we see the little bars on the computer's graphic equaliser when we talk into the microphone, indicating that the mic is working
).
