focus

noun

1. (countable)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)A point of a conic at which rays reflected from a curve or surface converge.
3. (uncountable)The fact of the convergence of light on the photographic medium.

   “Unfortunately, the license plate is out of focus in this image.”

   “Not long ago, it was difficult to produce photographs of tiny creatures with every part in focus.[…]A photo processing technique called focus stacking has changed that. Developed as a tool to electronically combine the sharpest bits of multiple digital images, focus stacking is a boon to biologists seeking full focus on a micron scale.”

4. (uncountable)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)Something to which activity, attention or interest is primarily directed.

   “My studies are my main focus right now.”

7. (countable)The exact point of where an earthquake occurs, in three dimensions (underneath the epicentre).

   “The earthquake's focus was at exactly 37 degrees north, 18 degrees south, seventy five meters below the ground.”

8. (countable, uncountable)The status of being the currently active element in a user interface, often indicated by a visual highlight.

   “Text entered at the keyboard or pasted from a clipboard is sent to the component which currently has the focus.”

9. (countable, uncountable)The most important word or phrase in a sentence or passage, or the one that imparts information.
10. (countable, uncountable)An object used in casting a magic spell.

    “Candles, in fact, are an essential ingredient in many spells. They can be used as either the focus of the spell or as a component that sets the spell's overall mood and tone.”

11. (countable, uncountable)The centre of an older fish's scale, which is the point where a younger fish's scale starts to grow from.

verb

1. (transitive)To cause (rays of light, etc) to converge at a single point.

   “The difficulties of focussing colour-light signals on curved tracks to ensure maximum sighting distance were underlined in the recent official report [...] on a low-speed collision at Newcastle Central on July 25, 1960, between an unfitted freight and a diesel-hauled passenger train.”

2. (transitive)To adjust (a lens, an optical instrument) in order to position an image with respect to the focal plane.

   “You'll need to focus the microscope carefully in order to capture the full detail of this surface.”

3. (intransitive, usually)To adjust itself or be adjusted such that light from a scene converges appropriately to create a clear image.

   “I can't get the lens to focus.”

   “The camera focuses automatically on the subject's eyes.”

4. (transitive)To direct attention, effort, or energy to a particular audience or task.

   “The president focused her remarks on the newcomers.”

5. (intransitive)To concentrate one’s attention.

   “If you're going to beat your competitors, you need to focus.”

6. (intransitive)To concentrate one's attention on something; to have as one's central point of interest, concern, etc.

   “I have to focus on my work.”

7. (transitive)To transfer the input focus to (a visual element), so that it receives subsequent input.

   “The text box won't receive the user's keystrokes unless you explicitly focus it.”

8. To aggregate figures of accounts.

   “Whole pages of it are filled with masses of figures, generally single numbers added up in batches, and then the totals added in batches again, as though he were "focusing" some account, as the auditors put it.”