backs
n. countable A1 Beginner US //ˈbæks// UK //bˈæks// backs
n. the rear part of the human body from the neck to the waist. You also use this word for the part of a chair that supports you when you sit.
n. the posterior part of the human body extending from the neck to the pelvis. Also refers to the side of an object that is opposite the front or the part of a seat that supports the spine.
He carries a heavy bag on his back every day.
After sitting at the computer for eight hours, her back felt stiff and sore.
The athlete suffered a strain in the lower muscles of his back during the final set of the competition, forcing him to withdraw from the remaining events.
Usage
Commonly used in the plural 'backs' when referring to the anatomy of multiple people or the rear supports of several chairs.