|For the noun: ||focus|
|Plural form: ||focuses, foci|
WordReference Random House Learner's Dictionary of American English © 2015
fo•cus /ˈfoʊkəs/USA pronunciation
n., pl. -cus•es, -ci /-saɪ, -kaɪ/USA pronunciation v., -cused, -cus•ing or (esp. Brit.)-cussed, -cus•sing. WordReference Random House Unabridged Dictionary of American English © 2015
[countable] a central point, such as of attraction, attention, or activity:His focus was on earning a living.
Physics[countable] a point at which rays of light, heat, or other radiation meet after being refracted or reflected.
Optics[uncountable] the adjustment of an optical device that is necessary to produce a clear image:The image is in focus.
to (cause to) come to a focus or into focus: [~ + object]to focus the lens of a camera.[no object]For a few moments my eyes wouldn't focus.
to concentrate: [~ + object]I tried to focus my thoughts.[no object; (~ + on + object)]I tried to focus on the project.
(fō′kəs), n., pl. -cus•es, -ci (-sī, -kī),
v., -cused, -cus•ing or ([esp. Brit.])-cussed, -cus•sing.
a central point, as of attraction, attention, or activity:The need to prevent a nuclear war became the focus of all diplomatic efforts.
Physics[Physics.]a point at which rays of light, heat, or other radiation, meet after being refracted or reflected.
- the focal point of a lens.
- the focal length of a lens.
- the clear and sharply defined condition of an image.
Mathematics[Geom.](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. See diag. under ellipse, hyperbola, parabola.
Geology[Geol.]the point of origin of an earthquake.
[Pathol.]the primary center from which a disease develops or in which it localizes.
to bring to a focus or into focus:to focus the lens of a camera.
to concentrate:to focus one's thoughts.
to become focused.
- the position of a viewed object or the adjustment of an optical device necessary to produce a clear image:in focus; out of focus.
1 . center, heart, core, nucleus.
- Latin: fireplace, hearth
Collins Concise English Dictionary © HarperCollins Publishers::
focus /ˈfəʊkəs/ n ( pl -cuses, -ci / -saɪ -kaɪ -kiː/)
vb ( -cuses, -cusing, -cused, -cusses, -cussing, -cussed)
- a point of convergence of light or other electromagnetic radiation, particles, sound waves, etc, or a point from which they appear to diverge
- another name for focal point, focal length
- 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
- a point upon which attention, activity, etc, is directed or concentrated
- a fixed reference point on the concave side of a conic section, used when defining its eccentricity
- the point beneath the earth's surface at which an earthquake or underground nuclear explosion originates
- the main site of an infection or a localized region of diseased tissue
Etymology: 17th Century: via New Latin from Latin: hearth, fireplaceˈfocuser n
- to bring or come to a focus or into focus
- (transitive) often followed by on: to fix attention (on); concentrate
'focus' also found in these entries: