because some idiot decided to call it that when it first started because they said it sounded funny sayin boxing square or any other thing to do with straight sides and pointed edges did that help? ;P
A boxer.
rig
6400 square ft 80 multiplied by 80 = 6400 square ft
A purse.
The supervisor in the oil rig office will call a helicopter to take you from the rig to the secret island prison.
square.
They call a square a square.
kayo
Presumably when it's a boxing ring where rounds are fought on a designated square area.
Apron
Tompkins Square Park