lounge chair
A type of outdoor furniture that allows a sunbather to recline in a relaxed position. Often found at a beach or at poolside, possibly in conjunction with a parasol. Also known as a sun lounger, chaise lounge (US), or deck chair (UK).
They serve a similar purpose as a deck chair, though a deck chair is a type of folding chair (with a fabric or vinyl strip that forms the seat and backrest, e.g. Danbooru post #1159067) and the shapes are reversed. A sun lounger has a longer seat than back, while a deck chair has a longer back than seat.