It's short for "category five", which is a type of cabling. The "Cat 5" part refers to the technical specifications of the cable, such as the bandwidth. Cat 5 cable is (usually) unshielded twisted-pair.
Cat-5 has 4 pairs and 8 wires
Cat-5 has 4 pairs and 8 wires
Cat 5, Cat 5e, Cat 6, Cat7
Cat Santarosa is 5' 7".
Cat Power is 5' 8".
Cat Noel is 5' 2".
Cat McCormick is 5' 8".
Cat Eberwine is 5' 2".
Cat Hannah is 5' 6".
Cat Hardy is 5' 4".
Cat Youell is 5' 7".
Abbie Cat is 5' 7".