backrest; back of a chair
Refers to the part of a chair, seat, or bench that supports the back.
この椅子は背もたれが低い。
This chair has a low backrest.
背もたれに寄りかかって休んだ。
I leaned back against the backrest and rested.
I reclined the backrest of the shinkansen seat and relaxed.
I was tired, so I leaned back against the chair's backrest and rested.
This bench doesn't have a backrest, so it's uncomfortable to sit on.
I adjusted the office chair's backrest to my liking.