noun
/ˈfoʊkəs/ , pl foci /ˈfoʊˌsaɪ/ also focuses
[count] :a subject that is being discussed or studied :the subject on which people's attention is focused - usually singular
a main purpose or interest [noncount]
[count] technical :a point at which rays of light, heat, or sound meet or from which they move apart or appear to move apart especially; :the point at which an image is formed by a mirror, a lens, etc.
[noncount] a state in which something (such as a camera, a telescope, or a person's eyes) produces a clear picture or image
a state in which the small details of a picture or image can be clearly seen
a state or condition in which something can be clearly understood
verb
-cuses also -cusses; -cused also -cussed; -cusing also -cussing
[+ obj] :to cause (something, such as attention) to be directed at something specific - + on
[no obj] :to direct your attention or effort at something specific
to adjust (something, such as a lens or a camera) to make an image clear [+ obj]
If you focus your eyes on something or if your eyes focus on something, you look at that thing so that you can see it clearly.
technical :to cause (light) to come together at a point [+ obj]