The word "vergence" refers to the ability to focus on objects at different distances, and it is commonly used in ophthalmology. There are a few synonyms for this word that can be used interchangeably. One of them is "convergence," which refers to the ability of the eyes to move together in order to focus on a nearby object. Another synonym for "vergence" is "accommodation," which is the ability of the eyes to adjust the shape of their lenses to focus on objects at different distances. Finally, "focusing ability" can also be used as a synonym for "vergence," and it describes the same concept of being able to see clearly at different distances.