Selectivity means being choosy or particular about what you accept, include, or allow. When a school has high selectivity, it only admits a small percentage of applicants: they might receive 1,000 applications but accept only 100 students. When a museum curator shows selectivity in choosing artwork for an exhibition, she carefully picks pieces that fit her vision rather than including everything available.

The word suggests deliberate judgment and high standards. A baseball team practicing selectivity at the plate doesn't swing at every pitch: they wait for good pitches they can actually hit. A reader showing selectivity doesn't read every book they encounter: they choose books that match their interests or challenge them in meaningful ways.

Selectivity isn't the same as being randomly picky or difficult. It means having clear criteria and sticking to them. A college with high selectivity looks for specific qualities in students. A scientist designing an experiment needs selectivity in choosing which variables to test.

The adjective form is selective. Someone might have a selective memory, remembering some things but conveniently forgetting others. A selective eater only likes certain foods. The key idea is choosing carefully from available options rather than accepting everything that comes your way.