Longitudinal waves are also called

Sound is a mechanical wave that results from the back and forth vibration of the particles of the medium through which the sound wave is moving. If a sound wave is moving from left to right through air, then particles of air will be displaced both rightward and leftward as the energy of the sound wave passes through it. The motion of the particles is parallel to the direction of the energy transport. This is what characterizes sound waves in air as longitudinal waves.
Longitudinal waves, also known as l-waves, are waves in which the displacement of the medium is in the same direction as, or the opposite direction to, the direction of travel of the wave.
Longitudinal waves are also called compressional waves or compression waves, because they produce compression and rarefaction when traveling through a medium. In longitudinal waves, the displacement of the medium is parallel to the propagation of the wave.