WordReference Random House Unabridged Dictionary of American English © 2026
de•fo•cus
(dē fō′kəs),USA pronunciation v., -cused, -cus•ing or (esp. Brit.) -cussed, -cus•sing, n., pl. -cus•es.
v.t.
v.i.
n.
v.t.
- to cause loss of focus of:The slightest movement will defocus the microscope.
- to interrupt or disturb (concentration, attention, etc.).
- to disturb the concentration or awareness of (someone).
v.i.
- to lose or go out of focus.
- to lose concentration or awareness;
become distracted.
n.
- the result of defocusing, as a blurred photographic image.
- de- + focus 1930–35