Noun - focus, Plural - countable and uncountable; foci or focuses
- 1. (countable) (optics) a point at which reflected or refracted rays of light converge.
The heat of sunlight at the focus of a magnifying glass can easily set dry leaves on fire.
- 2. (countable) (geometry) a point of a conic at which rays reflected from a curve or surface converge.
- 3. (uncountable) (photography, cinematography) The fact of the convergence of light on the photographic medium.
Unfortunately, the license plate is out of focus in this image.
- 4. (uncountable) (photography, cinematography) The quality of the convergence of light on the photographic medium.
During this scene, the boy’s face shifts subtly from soft focus into sharp focus.
- 5. (uncountable) concentration of attention.
I believe I can bring the high degree of focus required for this important job.
- 6. (countable) the exact point of where an earthquake occurs, in three dimensions.
The earthquake's focus was at exactly 37 degrees north, 18 degrees south, seventy five meters below the ground.