focus

[ foh-kuhs ]
See synonyms for focus on Thesaurus.com
noun,plural fo·cus·es or (especially British) fo·cus·ses, fo·ci [foh-sahy, -kahy]. /ˈfoʊ saɪ, -kaɪ/.
  1. a central point, as of attraction, attention, or activity: The need to prevent a nuclear war became the focus of all diplomatic efforts.

  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.

  1. 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.

  2. Physics. a point at which rays of light, heat, or other radiation meet after being refracted or reflected.

  3. Optics.

    • the focal point of a lens, on which rays converge or from which they deviate.

    • the focal length of a lens; the distance from a focal point to a corresponding principal plane.

    • the clear and sharply defined condition of an image.

    • the position of a viewed object or the adjustment of an optical device necessary to produce a clear image: in focus; out of focus.

  4. 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.

  5. Geology. the point of origin of an earthquake.

  6. 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.

Origin of focus

1
First recorded in 1635–45; Latin: “fireplace, hearth”

Other words for focus

Other words from focus

  • fo·cus·a·ble, adjective
  • fo·cus·er, noun
  • mis·fo·cus, verb, mis·fo·cused, mis·fo·cus·ing or (especially British) mis·fo·cussed, mis·fo·cus·sing.
  • mis·fo·cused, adjective
  • mis·fo·cussed, adjective
  • o·ver·fo·cus, verb (used with object), o·ver·fo·cused, o·ver·fo·cus·ing or (especially British) o·ver·fo·cussed, o·ver·fo·cus·sing.
  • re·fo·cus, verb, re·fo·cused, re·fo·cus·ing or (especially British) re·fo·cussed, re·fo·cus·sing.
  • 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

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2024

British Dictionary definitions for focus

focus

/ (ˈfəʊkəs) /


nounplural -cuses or -ci (-saɪ, -kaɪ, -kiː)
  1. a point of convergence of light or other electromagnetic radiation, particles, sound waves, etc, or a point from which they appear to diverge

  1. 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

  2. a point upon which attention, activity, etc, is directed or concentrated

  3. geometry a fixed reference point on the concave side of a conic section, used when defining its eccentricity

  4. the point beneath the earth's surface at which an earthquake or underground nuclear explosion originates: Compare epicentre

  5. pathol the main site of an infection or a localized region of diseased tissue

verb-cuses, -cusing, -cused, -cusses, -cussing or -cussed
  1. to bring or come to a focus or into focus

  2. (tr often foll by on) to fix attention (on); concentrate

Origin of focus

1
C17: via New Latin from Latin: hearth, fireplace

Derived forms of focus

  • focusable, adjective
  • focuser, noun

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Scientific definitions for focus

focus

[ kəs ]


Plural focuses or foci (sī′, fōkī′)
  1. The degree of clarity with which an eye or optical instrument produces an image.

  1. A central point or region, such as the point at which an earthquake starts.

  2. Mathematics A fixed point or one of a pair of fixed points used in generating a curve such as an ellipse, parabola, or hyperbola.

  3. The region of a localized bodily infection or disease.

The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.