sitter

Concise Oxford English Dictionary © 2008 Oxford University Press:
sitter/ˈsɪtə(r)/

▶noun

• 1 a person who sits, especially for a portrait or examination.

  ■ a sitting hen.

• 2 [usu. in combination] a person who looks after children, pets, or a house while the parents or owners are out or away: a house-sitter.

  ■ a person who provides care and companionship for people who are ill.

• 3 Brit. informal (in sport) an easy catch or shot.