1. a compartment with two airtight doors that allows people or objects to move between areas of different air pressure, especially in spacecraft or submarines
Usage: common in aerospace and underwater contexts
2. a pocket of air trapped in a pipe or tube that blocks the flow of liquid
Usage: plumbing and mechanical contexts

Examples

• The astronaut entered the airlock before stepping onto the lunar surface.
• The spacecraft's airlock depressurized slowly to equalize the pressure.
• An airlock in the water pipe prevented the pump from working properly.
• The submarine crew used the airlock to enter and exit the vessel safely.
• The plumber bled the radiator to remove an airlock that was blocking heat flow.
• Mission control confirmed that the airlock doors were sealed and secure.