1 [count] : a subject that is being discussed or studied : the subject on which people's attention is focused — usually singular ▪ The focus of our discussion/debate/attention will be drug abuse. ▪ The scandal became the primary focus of the day's news coverage. ▪ The study's main focus is adults with sleep disorders. 2 : a main purpose or interest [noncount] ▪ He's successful, but he feels that his life lacks focus. [singular] ▪ His life lacks a focus. 3 [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. 4 [noncount] a : a state in which something (such as a camera, a telescope, or a person's eyes) produces a clear picture or image
▪ bringing the binoculars into focus [=focusing the binoculars; adjusting the binoculars so that the image seen through them is clear and sharp] ▪ It took him a few seconds after he woke up to bring his eyes into focus. [=to focus his eyes] ▪ The binoculars were not in focus. = The binoculars were out of focus. [=the binoculars were not focused]
b : a state in which the small details of a picture or image can be clearly seen
▪ It was a nice picture—the family was in focus and everyone was smiling. ▪ Unfortunately, several of the pictures were out of focus. — see also soft focus
c : a state or condition in which something can be clearly understood
▪ She tried to bring the important issues into focus. [=she tried to say clearly what the important issues were]