Jax
Boy
A short form that stands alone. Jax works as a given name in its own right and as a short form of Jackson. You can choose the three-letter name without choosing Jackson for the birth certificate.
The meaning comes through Jackson. The Jackson connection carries the sense “son of Jack”. A Jack or Jackson in your family may be part of the appeal.
This is a Jackson-linked reading, not a universal literal meaning of Jax.