focus

noun (plural focuses or foci /ˈfōˌsī, -ˌkī/)

• 1the center of interest or activity:this generation has made the environment a focus of attention
• an act of concentrating interest or activity on something:our focus on the customer’s requirements
• Geology the point of origin of an earthquake. Compare with epicenter.
• Medicine the principal site of an infection or other disease.
• Linguistics the part of a sentence given prominence, usually for emphasis or contrast, e.g., Bob in it was Bob who came, not Bill. Compare with rheme.

• 2the state or quality of having or producing clear visual definition:his face is rather out of focus
• another term for focal point.
• the point at which an object must be situated with respect to a lens or mirror for an image of it to be well defined.
• a device on a lens that can be adjusted to produce a clear image.

• 3 Geometry one of the fixed points from which the distances to any point of a given curve, such as an ellipse or parabola, are connected by a linear relation.

verb (focuses, focusing, focused or focusses, focussing, focussed)

• 1(of a person or their eyes) adapt to the prevailing level of light and become able to see clearly:try to focus on a stationary object
• [with object] cause (one’s eyes) to focus:trying to focus his bleary eyes on Corbett
• [with object] adjust the focus of (a telescope, camera, or other instrument):they were focusing a telescope on a star
• (of rays or waves) meet at a single point.
• [with object] (of a lens) make (rays or waves) meet at a single point.
• [no object] (of light, radio waves, or other energy) become concentrated into a sharp beam of light or energy.
• [with object] (of a lens) concentrate (light, radio waves, or energy) into a sharp beam.

• 2 (focus on) pay particular attention to:the study will focus on a number of areas in Wales
• [with object] concentrate:the course helps to focus and stimulate your thoughts
• [with object] Linguistics place the focus on (a part of a sentence).