2 n. a person under the zodiac sign of Aquarius; an Aquarian.
3 n. an infant who dies by drowning.
2. "She's a waterbaby, so she'll go perfect with me being a Leo."
3. "It's so sad...what a sweet child to die a waterbaby."
Another great example of a water baby would be Percy Jackson from the movie "Percy Jackson and the Olympians". Percy says that whenever he is in the water, he can think more clearly on things.
"That Percy Jackson character is a total water baby version of Zac Effron."