A kitten (also known as a kitty or kitty cat) is a juvenile domesticated cat. After being born, kittens are totally dependent on their mother for survival and do not normally open their eyes until after seven to ten days. After about two weeks, kittens quickly develop and begin to explore the world outside the nest. After a further three to four weeks, they began to eat solid food and grow adult teeth. Kittens are highly social animals and enjoy human companionship.
The word "kitten" derives from the Middle English word kitoun, which in turn came from the Old French chitoun or cheton. The young of big cats are called "cubs" rather than kittens; either term may be used for the young of smaller wild felids, such as ocelots, caracals and lynx, but "kitten" is usually more common for these species.
A feline litter usually consists of two to five kittens. The kits are born after a gestation that lasts between 64 and 67 days, with an average length of 66 days. Kittens emerge in a sac called the amnion, which is bitten off and eaten by the mother cat.
For the first several weeks, kittens are unable to urinate or defecate without being stimulated by their mother. They are also unable to regulate their body temperature for the first three weeks, so kittens born in temperatures less than 27 °C (81 °F) can die from hypothermia if they are not kept warm by their mother.