bent nail; crooked nail
A nail that has been bent, often accidentally or for reuse. Not a specialized hardware term.
I hammered the bent nail straight.
L-shaped hook; square bend screw hook
A nail or screw with a right-angle bend, used as a hook for hanging items. Often called an 'L hook' in hardware contexts.
I drove an L-shaped hook into the wall and hung a calendar.
Compound of 折れ (bent, from 折れる) and 釘 (nail). The meaning 'L-shaped hook' comes from the right-angle bend resembling a bent nail.