| Noun | 1. | Sitter - Dutch astronomer who calculated the size of the universe and suggested that it is expanding (1872-1934) | |
| 2. | sitter - an organism (person or animal) that sitsorganism, being - a living thing that has (or can develop) the ability to act or function independently stander - an organism (person or animal) that stands; "a crowd of sitters and standers" | |
| 3. | sitter - a person engaged to care for children when the parents are not homekeeper - someone in charge of other people; "am I my brother's keeper?" | |
| 4. | sitter - a person who poses for a painter or sculptorposer, model - a person who poses for a photographer or painter or sculptor; "the president didn't have time to be a model so the artist worked from photos" | |
| 5. | sitter - a domestic hen ready to brood | |