lock
The primary image is one of total restriction and security. It suggests a binary state: either something is open and accessible, or it is closed and impenetrable. This creates a feeling of finality and safety, but in social contexts, it can imply exclusion or secrecy.
Countable when referring to a physical device or a piece of hair. Uncountable when referring to the state of being locked.
Meanings
A mechanical device used to secure a door or container.
The lock on the front door is broken.
A section of a canal with gates that can be closed to raise or lower water levels.
The boat slowly entered the lock to reach the upper canal.
To fasten something with a lock.
Please lock the gate before you leave.
Examples
The heavy iron lock on the chest was rusted shut.
A golden lock of hair fell across her forehead.
The barge waited for the lock gates to open.
Remember to lock the front door before you go to bed.
The safety mechanism will lock the blade in place.
The wheels may lock if you brake too suddenly.
Phrasal Verbs
lock up
to secure a building or room by locking all doors and windows
The manager told the staff to lock up the office before leaving for the night.
lock out
to prevent someone from entering a place by locking the door
I accidentally locked myself out of the house.
lock in
to confine someone or something in a place by locking the door
The security guard locked the suspects in the holding cell.
lock down
to restrict movement or access to a location for security reasons
The school was locked down during the police operation.
lock onto
to acquire and maintain a target or signal
The missile system locked onto the incoming aircraft.