Babysitting is taking care of someone else's children for a short time while the parents are out — an evening, a Saturday afternoon, not years of raising the child. You babysit (the verb); the work is babysitting; the person is a babysitter. A lot of teenagers do it for neighbours; some people do it as paid work. The baby in the word is used loosely: you can babysit a school-age child. What it does not mean is a full-time nanny, a nursery school, or looking after your own brothers and sisters as your main job, though families stretch the word that way sometimes. It is an informal, everyday word, more home than office.