sitter

One that sits, especially.

A person who cares for young children when the parents are not home; a babysitter.

A person who poses or models, as for a portrait.

A brooding hen.

In cricket: An easy catch missed by a fielder.

A fielder who misses such a catch.

One who or that which sits

A brooding or incubating bird.

One who takes a certain posture, position, or course in order to a particular end; specifically, one who poses to an artist for a portrait, bust, or the like.

One who watches during the night.