Pronunciation: (dē-fō'kus),[key] —v.,-cused, -cus•ing or (esp. Brit.)-cussed, -cus•sing, —n., pl.-cus•es.
—v.t. 1. to cause loss of focus of: The slightest movement will defocus the microscope. 2. to interrupt or disturb (concentration, attention, etc.).
3. to disturb the concentration or awareness of (someone).
—v.i. 1. to lose or go out of focus.
2. to lose concentration or awareness; become distracted.
—n. the result of defocusing, as a blurred photographic image.