What is "unbolts"

Usage examples of "unbolts".

A TV monitor broods over the heavy door, and I have to feed a plastic card into the lock and punch in a personal number before the door unbolts itself letting me into an airlock and a second door before I get into the animal house proper.

Yet on the third night she actually unbolts it herself and leaving it unbolted puts out her light and goes to bed.

Imagine then that the old bolt is unscrewed, rubbed with emery paper, bathed in paraffin, polished with fine sand, generously oiled, and reset by a skilled workman with such nicety that it bolts and unbolts with the pressure of a finger—with the pressure of a feather—almost so that you could blow it open or shut.