The name Pegasus is a boy's name meaning "from a water spring".
The white winged stallion in Greek mythology who sprang from the blood of Medusa when she was beheaded by Perseus. Pegasus was ridden by the hero Bellerophon in his fight against the Chimera. The name may derive from the Greek for "from a water spring"; according to legend, a spring burst forth wherever Pegasus struck the earth with a hoof. So as well as being an animal name and a mythological name, you might consider this one of the names meaning water.