focus
/ˈfəʊ.kəs//ˈfoʊ.kəs/noun
Definitions
A point at which reflected or refracted rays of light converge.
Example: The heat of sunlight at the focus of a magnifying glass can easily set dry leaves on fire.
A point of a conic at which rays reflected from a curve or surface converge.
The fact of the convergence of light on the photographic medium.
Example: Unfortunately, the license plate is out of focus in this image.
The quality of the convergence of light on the photographic medium.
Example: During this scene, the boy’s face shifts subtly from soft focus into sharp focus.
verb
Definitions
(followed by on or upon) To concentrate one's attention.
Example: I have to focus on my work.
To cause (rays of light, etc) to converge at a single point.
To adjust (a lens, an optical instrument) in order to position an image with respect to the focal plane.
Example: You'll need to focus the microscope carefully in order to capture the full detail of this surface.
To concentrate one’s attention.
Example: If you're going to beat your competitors, you need to focus.