1. To cause (light rays, for example) to converge on or toward a central point; concentrate.
2.
a. To render (an object or image) in clear outline or sharp detail by adjustment of one's vision or an optical device; bring into focus.
b. To adjust (a lens, for example) to produce a clear image.
3. To direct toward a particular point or purpose: focused all their attention on finding a solution to the problem.
v.intr.
1. To converge on or toward a central point of focus; be focused.
2. To adjust one's vision or an optical device so as to render a clear, distinct image.
3. To concentrate attention or energy: a campaign that focused on economic issues.