1. a person or thing that excludes or keeps out
Usage: often used in beekeeping to refer to a device that prevents larger bees or the queen from passing through
2. a device or mechanism designed to prevent entry or passage of something specific
Usage: technical or specialized use

Examples

• The beekeeper installed a queen excluder to keep the queen bee out of the honey storage area.
• A predator excluder protects young plants from being eaten by wildlife.
• The excluder prevented larger particles from entering the water filtration system.
• Beekeepers rely on excluders to manage the movement of bees within the hive.
• The mesh excluder allowed small insects through while blocking larger pests.