lock

This word usually brings to mind a device that keeps something shut or safe, like the one on a door, a box, or a phone. As a verb, it means to close something so others cannot open it, or to fix something firmly in place. You can lock a bike to a fence, lock a drawer, or lock your screen before you walk away.

It also appears in a few other common ways. A lock of hair is a piece of hair, often a curl. A canal lock is the part of a waterway that lifts or lowers boats between different water levels. In a more figurative way, people can be locked in a struggle, a habit, or a plan, which gives the sense of being fixed, trapped, or hard to change.

The word "lock" has several related meanings, and the main idea is usually security, control, or something being fixed in place. Most often, it is a noun for the device that keeps a door, gate, box, or other container shut, usually opened with a key, code, card, or similar method. As a verb, it means to secure something in that way: you lock a house before leaving, lock a suitcase before a trip, or lock a phone so other people cannot use it.

The word also has a few important noun senses beyond security devices. A lock of hair is a piece or curl of hair. A canal lock is a gated section of a canal that raises or lowers boats as water levels change. In older or technical use, lock can also mean a tuft of wool or similar fiber, and in firearms it can mean the part that sets off the charge.

In figurative use, "lock" often suggests that movement or change has become limited. Someone may feel locked into an agreement, a routine, or a way of thinking. Two people can be locked in an argument or a close contest. Related words such as deadlock and gridlock keep the same idea of something being blocked or unable to move forward. Across these uses, the word keeps a clear thread: it is about closing, securing, holding fast, or preventing easy change.