from The Century Dictionary and Cyclopedia
- n. A form of lock in which the bolt is a projecting cylindrical pin.
- n. A poundmaster's fee.
Sorry, no etymologies found.
So on the first day I tried the new equipment I asked a guy working out near me who was using the same kind of weights how the new pin-lock worked (because if it isn't locked, it was clear the big hurt could happen).
Explaining: my gym got new equipment, that has a pin-lock component I hadn't seen before.