A lockout is when someone who owns or controls a building or workplace deliberately prevents other people from entering it, usually during a disagreement or conflict.

The term comes up most often in labor disputes. When workers go on strike and refuse to work until their demands are met, their employer might respond with a lockout, literally locking the workers out of the factory, office, or workplace until the workers agree to the company's terms. It's like a strike in reverse: instead of workers choosing to stay away, the employer chooses to keep them away.

Lockouts can also happen in sports. When professional team owners and players disagree about contracts or rules, the owners might declare a lockout, preventing players from practicing or playing games until an agreement is reached. The 2011 NBA lockout, for example, delayed the start of the basketball season for months.

The word can also describe any situation where someone is physically locked out of a place they need or want to enter, like when you accidentally lock yourself out of your house and have to wait for someone with a spare key. But the most significant use of the term involves deliberate shutdowns during disputes over money, working conditions, or rules.