WordReference Random House Learner's Dictionary of American English © 2015
fo•cus /ˈfoʊkəs/USA pronunciation
n., pl. -cus•es, -ci/-saɪ, -kaɪ/USA pronunciationv., -cused, -cus•ingor (esp. Brit.)-cussed, -cus•sing.
[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.
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: