Noun
a support that you can lean against while sitting
Source: WordNetthe back of the dental chair was adjustable Source: Internet
The Ram 1500’s is awesome, changing from a three-seater to two highly comfortable cloth buckets by simply folding down the center seat’s backrest, which becomes an armrest with two cupholders and a spacious cubby. Source: Internet
In fact, the backrest can even recline so far back that users could prop up their legs and be practically laying flat. Source: Internet
With the turn of a dial, users can determine how much or how little they want the lower portion of the backrest to firm up. Source: Internet
Now place both the hands on either sides of the backrest. Source: Internet
Use an extra mattress as a backrest. Source: Internet