Focus is a versatile English word with multiple meanings:
1. As a noun: the main or central point of something, especially of attention or interest.
2. As a verb: to concentrate attention or effort on something.
3. In photography: the point at which an object must be situated for its image to be clear.
4. In physics: the point at which rays or waves meet after reflection or refraction.
5. In geology: the point of origin of an earthquake.