defocus

[ dee-foh-kuh s ]
/ diˈfoʊ kəs /

verb (used with object), de·fo·cused, de·fo·cus·ing or (especially British) de·fo·cussed, de·fo·cus·sing.

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).

verb (used without object), de·fo·cused, de·fo·cus·ing or (especially British) de·fo·cussed, de·fo·cus·sing.

to lose or go out of focus.
to lose concentration or awareness; become distracted.

noun, plural de·fo·cus·es.

the result of defocusing, as a blurred photographic image.

Origin of defocus

First recorded in 1930–35; de- + focus