Real Dictionary

lock out
phrasal verb: If someone locks you out of a place, they prevent you entering it by locking the doors.

lock out in American English
to keep out by or as if by a lock
to shut out by or as by locking the door against

lock out in British English
to prevent from entering by locking a door
noun: the closing of a place of employment by an employer, in order to bring pressure on employees to agree to terms

lock-out
countable noun: A lock-out is a situation in which employers close a place of work and prevent workers from entering it until the workers accept the employer's new proposals on pay or conditions of work.