A kid is a child, informally, and it's also a young goat. ... When kid is used as a verb, it means to tease or jokingly deceive someone — to kid them. Some sticklers for formality object to using kid to mean "child," but that meaning has been around since the 1590s.
Anyhow, what age is a kid?
The United Nations Convention on the Rights of the Child defines child as "a human being below the age of 18 years unless under the law applicable to the child, majority is attained earlier".
For all that, is 14 still a kid? Yes, you are most certainly still a child. Some people of that age prefer to be known as a young person, but legally you are still a child. You're a teen/teenager/young person.
Accordingly, why are children called Kids?
It was considered informal English by the mid-19th century and is now in common use. The kids' referred to when the word first referred to children were sold by criminals to sea captains who took them to British colonies as labourers or slaves. They were also youngsters enlisted by British sailors or soldiers.
Is Kid A slang word?
Is the word kid slang? ... In contemporary English, kid is neither slang nor improper. It is, however, most definitely informal, so those writing professionally or in a formal register might prefer to use child.