A seat is a place to sit. The term may encompass additional features, such as back, armrest, head restraint but also headquarters in a wider sense. Types of seat The following are examples of different kinds of seat: Armchair, a chair equipped with armrests Airline seat, for passengers in an aircraft Bar stool, a high stool used in bars and many houses Bench, a long hard seat Bicycle seat, a saddle on a bicycle Car seat, a seat in an automobile Cathedra, a seat for a bishop located in a cathedral Chair, a seat with a back Chaise longue, a soft chair with leg support Couch, a long soft seat Ejection seat, rescue seat in an aircraft Folding seat Hard seat Infant car seat, for a small child in a car Jump seat, auxiliary seat in a vehicle Pew, a long seat in a church, synagogue, or courtroom Saddle, a type of seat used on the backs of animals, bicycles, lap etc. Sliding seat, in a rowing boat Sofa, alternative name for couch Stool, a seat with no armrests or back Throne, a seat for a monarch Etymology The word seat comes from Middle English sete, Old English gesete/geseten and/or sǣte seat, sittan to sit. Possibly related to or cognate with Old Norse sæti. The first known use of the word seat is in the 13th century. Ergonomics For someone seated, the 'buttock popliteal' length is the horizontal distance from the rearmost part of the buttocks to the back of the lower leg. This anthropometric measurement is used to determine seat depth. Mass-produced chairs typically use a depth of . See also Chair Seating assignment Seating capacity References Furniture de:Möbel#Sitzmöbel