If it came from an egg, it's a hatchling, or neonate. If it was born live, it's a neonate. Once it grows a bit bigger, but still isn't an adult, it's called a juvenile. read more
A baby lizard is often referred to as a hatchling, though this term is not exclusive to lizards as most animals that are hatched from eggs can also be referred to as such. It is possible that some individual species may have more specific names for their babies. read more