focus

[ foh-kuhs ]

noun

, plural fo·cus·es or (especially British) fo·cus·ses, fo·ci [foh, -sahy, -kahy].

1. a central point, as of attraction, attention, or activity:

   The need to prevent a nuclear war became the focus of all diplomatic efforts.

   Synonyms: nucleus, core, heart, center

2. close attention or concentration:

   Some of the warning signs indicating you should pull over: drifting between lanes, repeated yawning, tailgating, and trouble maintaining focus.

3. the ability to concentrate one’s attention or to sustain concentration:

   Mindfulness and meditation are often suggested to help manage stress, increase awareness of emotions, and improve focus.

4. Physics. a point at which rays of light, heat, or other radiation meet after being refracted or reflected.
5. Optics.
   1. the focal point of a lens, on which rays converge or from which they deviate.
   2. the focal length of a lens; the distance from a focal point to a corresponding principal plane.
   3. the clear and sharply defined condition of an image.
   4. the position of a viewed object or the adjustment of an optical device necessary to produce a clear image:

      in focus; out of focus.

6. Geometry. (of a conic section) a point having the property that the distances from any point on a curve to it and to a fixed line have a constant ratio for all points on the curve.
7. Geology. the point of origin of an earthquake.
8. Pathology. the primary center from which a disease develops or in which it localizes.

verb (used with object)

, fo·cused, fo·cus·ing or (especially British) fo·cussed, fo·cus·sing.

1. to bring to a focus or into focus; cause to converge on a perceived point:

   to focus the lens of a camera.

2. to concentrate:

   to focus one's thoughts;

   to focus troop deployment in the east.

verb (used without object)

, fo·cused, fo·cus·ing or (especially British) fo·cussed, fo·cus·sing.

1. to be or become focused:

   My eyes have trouble focusing on distant objects.

2. to direct one's attention or efforts:

   Students must focus in class.

focus

/ ˈfəʊkəs /

noun

1. a point of convergence of light or other electromagnetic radiation, particles, sound waves, etc, or a point from which they appear to diverge
2. See focal point, focal length
   another name for focal point focal length
3. optics the state of an optical image when it is distinct and clearly defined or the state of an instrument producing this image

   the picture is in focus

   the telescope is out of focus

4. a point upon which attention, activity, etc, is directed or concentrated
5. geometry a fixed reference point on the concave side of a conic section, used when defining its eccentricity
6. See epicentre
   the point beneath the earth's surface at which an earthquake or underground nuclear explosion originates Compare epicentre
7. pathol the main site of an infection or a localized region of diseased tissue

verb

1. to bring or come to a focus or into focus
2. troften foll byon to fix attention (on); concentrate

focus

/ fō′kəs /

, or foci fō′sī′,fō′kī′

1. The degree of clarity with which an eye or optical instrument produces an image.
2. See focal point
3. A central point or region, such as the point at which an earthquake starts.
4. Mathematics.
   A fixed point or one of a pair of fixed points used in generating a curve such as an ellipse, parabola, or hyperbola.
5. The region of a localized bodily infection or disease.

Derived Forms

• ˈfocuser, noun
• ˈfocusable, adjective

Other Words From

• fo·cus·a·ble adjective
• fo·cus·er noun
• mis·fo·cus verb misfocused misfocusing or (especially British) misfocussed misfocussing
• mis·fo·cused adjective
• mis·fo·cussed adjective
• o·ver·fo·cus verb (used with object) overfocused overfocusing or (especially British) overfocussed overfocussing
• re·fo·cus verb refocused refocusing or (especially British) refocussed refocussing
• self-fo·cused especially British, self-fo·cussed adjective
• self-fo·cus·ing especially British, self-fo·cus·sing adjective
• un·fo·cus·ing especially British, un·fo·cus·sing adjective
• well-fo·cused especially British, well-fo·cussed adjective

Word History and Origins

Origin of focus¹

First recorded in 1635–45; Latin: “fireplace, hearth”

Word History and Origins

Origin of focus¹

C17: via New Latin from Latin: hearth, fireplace

Example Sentences

In the intervening period, as we weighed the cost of our overall portfolio and strategic focus, we made the decision not to relaunch the service.

From TechCrunch

Several startups, including MJ Platform and BioTrack, are building similar platforms for this market, but Canix says the company’s focus on improving data entry makes it stand apart.

From TechCrunch

West Virginia environmental regulators are proposing to reduce the fines that a coal company owned by the state’s governor could pay for water pollution violations that are the focus of a federal court case.

From ProPublica

Initially there may be a limited supply of vaccines available, and the focus will be on protecting health workers, other essential employees, and people in vulnerable groups.

From Fortune

However, different aspects vary based on the agency’s focus.

From Search Engine Land

Back in New York, the slow pace and inward focus of her yoga practice was less fulfilling.

From The Daily Beast

Stephanie Giorgio, a classical musician, credits The Class for helping her cope with anxiety, focus, fear, and self-doubt.

From The Daily Beast

There is a particular focus in the magazine on attacking the United States, which al Qaeda calls a top target.

From The Daily Beast

And too much of a focus on numbers can obscure strategic truths.

From The Daily Beast

His wife passed away and they had kids, and he wanted to focus on being a dad so he just stopped to raise his kids.

From The Daily Beast

Lessard's high-handed squelching of MacRae had thrown everything out of focus.

From Project Gutenberg

William Weedham brought scowling eyes to focus upon Kip Burland.

From Project Gutenberg

It is doubtful if any woman had done as much to entice them to a common focus as the surmounting Mrs. Hofer.

From Project Gutenberg

Why the focus of the telescope should change during a long exposure is not quite clear.

From Project Gutenberg

Before beginning an exposure the focus is adjusted by means of a high-power positive eyepiece.

From Project Gutenberg

Related Words

• apply oneself to
• attend (to)
• concentrate
• engage
• fixate
• pay attention to
• pore over

What Is The Plural Of Focus?

Plural word for focus

The plural form of focus can be either focuses, focusses, or foci (pronounced [ foh-sahy] or [ foh-kahy ]). Focuses is the most commonly used plural form in nontechnical contexts in American English, while focuses is the most common in nontechnical contexts in British English. The plural foci is typically found only in technical contexts, as in physics, optics, or geometry. 

The plurals of several other singular words that end in -us are formed in the same way as foci, including fungus/fungi or cactus/cacti. 

Irregular plurals that are formed like foci derive directly from their original pluralization in Latin.

More About Focus

Where does focus come from?

What does the word focus bring to your mind? Maybe you think of a photograph that is clear and sharply defined. Or perhaps you recall a teacher tsk-tsking you to pay attention in class. But what about a fireplace?

Well, the word focus comes directly from the Latin focus, which meant “fireplace” or “hearth” (that is, the floor of a fireplace). This is what focus originally meant in English when the word entered the language around 1635–45, though that sense has been extinguished, as it were.

But the word focus burned on in other ways. As the 1600s unfolded, focus was given new meanings in the great scientific literature of that age, which were largely written in what’s known as New Latin. In the 1650s, the influential English philosopher and author Thomas Hobbes used focus for a kind of fixed point in geometry. So did Isaac Newton—you know, of gravity fame—in the 1690s.

Other applications of the word focus in the late 1600s came about in the fields of medicine and physics. In physics, a focus is “a point at which rays of light, heat, or other radiation meet after being refracted or reflected.” Perhaps you can imagine how a fireplace or a hearth—contained areas and sources of heat and light—was likened to such a point in math and science.

Dig deeper

The word focus took on a number of senses in optics, specifically “the point on a lens on which rays converge or from which they deviate.” A more familiar sense of focus is “the clear and sharply defined condition of an image,” as when the image isn’t blurry. Optics has also given us the expressions in focus and out of focus, which can be used both literally and figuratively.

From these various ideas of clarity and convergence in optics arises one of the more common, everyday ways we use the word focus today: “a central point, as a of attention, activity, or activity.” For example, Finding a cure for cancer was the focus of his long career. Focus also refers to ability to concentrate, as in The teacher felt the students struggled with their focus. These senses of focus had spread by the early 1800s, around when various verb forms of focus take off. The adjective form of focus is focal.

Did you know ... ?

The Latin word focus became the general word for “fire” in the language’s descendants. Spanish fuego, French fue, Italian fuoco, Portuguese fogo, Romanian foco, to cite just the most spoken Romance languages—all of these words for “fire” come from the Latin focus.

So does another French word for a different part of the house: the foyer. A foyer refers to a lobby of a theater, hotel, or apartment house. In French, a foyer was originally a room to which theater audiences went for warmth between the acts.

There’s just something about a fireplace, isn’t there? Its magic wasn’t lost on the ancient Romans, either: focus was also extended to mean “home, family,” a metaphor also at work in English’s very own word hearth. Now that warms the heart, doesn’t it?