This is a geographical place name, for the large sea between Asia and Europe. But like his beautiful namesake, you’ll still love your little Caspian, even if he gets a little salty.
Cas, Ian. Or Pian if you want to get back at him for spraying you in the face during a diaper change.
Famous people named Caspian:
Screenwriter Caspian Tredwell-Owen; one-named rapper Caspian; writer Jay Caspian Kang.
You’ll definitely want to read the C.S. Lewis novel Prince Caspian with your little prince.