Definition of focus in English:

focus

Syllabification: fo·cus
Pronunciation: /ˈfōkəs
 
/

noun (plural focuses or foci /ˈfōˌsī, -ˌkī/)

  • 1The center of interest or activity: this generation has made the environment a focus of attention
    More example sentences
    • But combine it with a programme that lacks a clear focus and Cork's year in the cultural spotlight is already looking shaky.
    • Once you have a clear focus, gather the right team around you to get the job done.
    • But if it keeps a clear focus it might achieve a way forward for our embattled province.
    Synonyms
    center, focal point, central point, center of attention, hub, pivot, nucleus, heart, core, cornerstone, linchpin, cynosure
  • 1.1An act of concentrating interest or activity on something: our focus on the customer’s requirements
    More example sentences
    • To be charitable, perhaps his paranoid focus on who'd been criticising Latham obscured his focus.
    • Focus on your own feelings and share them with your partner, so you won't lose the focus of your own body.
    • I relish the hours when my entire focus isn't concentrated on breathing.
    Synonyms
    emphasis, accent, priority, attention, concentrationsubject, theme, concern, subject matter, topic, issue, thesis, point, thread; substance, essence, gist, matter
  • 1.2 Geology The point of origin of an earthquake. Compare with epicenter.
    More example sentences
    • The geographic point directly above the focus is called the earthquake epicenter.
    • This result strongly agrees with the upward migration of seismic foci in the volcanic edifice, which has been found to precede recent flank eruptions.
  • 1.3 Medicine The principal site of an infection or other disease.
    More example sentences
    • There was extensive embolization to the brain and multiple foci of Aspergillus infection in kidneys and adrenal glands.
    • An identifiable focus of primary infection should also be addressed when possible.
    • The macroscopically apparent thrombosed vessels in case 3 contained tumor emboli and multiple foci of infarction.
  • 1.4 Linguistics The part of a sentence given prominence, usually for emphasis or contrast, e.g., Bob in it was Bob who came, not Bill. Compare with rheme.
  • 2The state or quality of having or producing clear visual definition: his face is rather out of focus
    More example sentences
    • It's only to be expected that most of the pictures are not of the highest quality, often out of focus or a bit blurred.
    • When she finally did open them, everything blurred out of focus, then came in clear.
    • I'm definitely one of those people who hears most music as a soundtrack to a film going on somewhere in my head, usually deeply out of focus.
    Synonyms
    focal point, point of convergencesharp, crisp, distinct, clear, well-defined, well focusedblurred, unfocused, indistinct, blurry, fuzzy, hazy, misty, cloudy, lacking definition, nebulous
  • 2.1 another term for focal point.
    More example sentences
    • While Zippy has the attention span of a goldfish, his wife has the focus of an electron microscope.
    • The probability for such an event occurring is only significant at the plane of focus, where photon flux is the highest.
    • Their focus was always upon the general rather than the particular.
  • 2.2The point at which an object must be situated with respect to a lens or mirror for an image of it to be well defined.
    More example sentences
    • In the Nasmyth focus, an oblong tertiary mirror is positioned in this opening and it reflects the light from the secondary mirror to foci located on either side of the telescope.
    • The problems with the microlens array design are low light throughput, non-uniform intensity foci, and lens aberrations.
    • There is a central hole in the main mirror through which the light passes and is brought to a focus by an eyepiece lens.
  • 2.3A device on a lens that can be adjusted to produce a clear image.
    More example sentences
    • He adjusts the focus of the Carl Zeiss 120 mm macro lens, which allows him to work very close up.
    • These lenses adjust their focus with a patient's eye muscles to give them seamless near or distance vision.
    • The focus can be adjusted slightly in order to sharpen up different parts of the image corresponding to objects at different depths in the scene.
  • 3 Geometry One of the fixed points from which the distances to any point of a given curve, such as an ellipse or parabola, are connected by a linear relation.
    More example sentences
    • The circumcircle of a triangle formed by three tangents to a parabola, passes through the focus of the parabola.
    • The focus and directrix of a parabola were considered by Pappus.
    • The catenary is the locus of the focus of a parabola rolling along a straight line.

verb (focuses, focusing, focused or focusses, focussing, focussed)

[no object] Back to top  
  • 1(Of a person or their eyes) adapt to the prevailing level of light and become able to see clearly: try to focus on a stationary object
    More example sentences
    • His blue eyes didn't seem to focus on any one person on the floor below him, but seemed to see all of them without focusing.
    • She could only see a blur at first, but her vision focused and she was able to see clearly her surroundings.
    • When she was able to focus, she saw two vamps descending on her.
  • 1.1 [with object] Cause (one’s eyes) to focus: trying to focus his bleary eyes on Corbett
    More example sentences
    • Feeling distinctly sick, he lay back down and focused his eyes, surveying his surroundings.
    • Every few metres the cat stopped and twisted its head around, focussing its yellow eyes on me, checking to see if I was still in pursuit.
    • I think some of the brain which attends to focussing my eyes may have leaked out.
  • 1.2 [with object] Adjust the focus of (a telescope, camera, or other instrument): they were focusing a telescope on a star
    More example sentences
    • For example, in one puzzle you have to focus a telescope, and to do so you have to add or remove 14 lenses.
    • I have written about this many times, but modern auto-focus cameras deliver more ‘out of focus’ shots than manually focussed cameras.
    • ‘Just look at me,’ says Juergen, focusing the camera.
    Synonyms
    bring into focus; aim, point, turn
  • 1.3(Of rays or waves) meet at a single point.
    More example sentences
    • These scatter the sun's rays, and prevent them from being focused together into a single bright point.
    • In narrow inlets and coves, the wave can become focused or amplified, reaching tens of metres in height.
    • Because gamma rays are hard to focus into sharp images, the science team then used the X-ray telescope on Swift to determine a precise location.
  • 1.4 [with object] (Of a lens) make (rays or waves) meet at a single point.
    More example sentences
    • When a lens system optimally focuses an incoming ray bundle, the spread of passed wavelengths is in focus at a range of points in front of, on, and behind the sensor focal plane.
    • When a lens is used to focus the sun's rays onto a piece of paper the distance of the paper from the lens is called the focal length.
    • And they were used for starting fires by focusing the rays of the sun.
  • 1.5 [no object] (Of light, radio waves, or other energy) become concentrated into a sharp beam of light or energy.
    More example sentences
    • It works like your grappling hook did, but instead of string, it uses gravity focused into a ‘beam’ to connect it.
    • In that time, the energy had focused and spiked beyond what I have ever felt before.
    • Normally a light beam will focus to a point no smaller than about the size of the light's wavelength.
  • 1.6 [with object] (Of a lens) concentrate (light, radio waves, or energy) into a sharp beam.
    More example sentences
    • An objective lens focuses the light onto a region approximately 1 mm in diameter and subsequently collects the light returning from the target.
    • The eye has a lens, and even ‘film’ (the retina), which detects light focused by the lens.
    • In the simple experiment, a converging lens focuses laser light from two pinholes onto two different photodetectors.
  • 2 (focus on) Pay particular attention to: the study will focus on a number of areas in Wales
    More example sentences
    • As his heart started to race, he drew his attention inward, focussing on his breathing.
    • The study focussed on a period of time beginning four years before the casino opened and four years after.
    • More studies focusing on this particular problem are needed before a conclusion can be drawn.
  • 2.1 [with object] Concentrate: the course helps to focus and stimulate your thoughts
    More example sentences
    • He concentrated, focusing his thoughts on the strange impressions he was receiving.
    • According to dharma, or divine law, temple worship is important because it focuses our concentration on God.
    • The concentration on punishment damages the national debate by focussing all attention on revenge.
    Synonyms
    concentrate on, center on, zero in on, zoom in on; address itself to, pay attention to, pinpoint, revolve around, have as its starting point
  • 2.2 [with object] Linguistics Place the focus on (a part of a sentence).

Derivatives

focuser

noun
More example sentences
  • Along with its atom stream turrets on port and starboard sides there are energy focusers to destroy anything under atmosphere.
  • He had two focusers floating on ether side of his head to represent his constant control.
  • A helical focuser is located at the rear of the body.

Origin

mid 17th century (as a term in geometry and physics): from Latin, literally 'domestic hearth'.

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