n.
Pronunciation: ' f ō -k ə s
Function: noun
Inflected Form: plural fo · ci \ ' f ō - ˌ s ī also - ˌ k ī \ also fo · cus · es
Etymology: New Latin, from Latin, hearth
Date: 1644
1 a : a point at which rays (as of light, heat, or sound) converge or from which they diverge or appear to diverge specifically : the point where the geometrical lines or their prolongations conforming to the rays diverging from or converging toward another point intersect and give rise to an image after reflection by a mirror or refraction by a lens or optical system b : a point of convergence of a beam of particles (as electrons)
2 a : FOCAL LENGTH b : adjustment for distinct vision also : the area that may be seen distinctly or resolved into a clear image c : a state or condition permitting clear perception or understanding <tried to bring the issues into focus > d : DIRECTION 6C <the team lost focus >
3 : one of the fixed points that with the corresponding directrix defines a conic section
4 : a localized area of disease or the chief site of a generalized disease or infection
5 a : a center of activity, attraction, or attention <the focus of the meeting was drug abuse> b : a point of concentration
6 : the place of origin of an earthquake or moonquake
7 : directed attention : EMPHASIS
– fo · cus · less \ -l ə s \ adjective
– in focus : having or giving the proper sharpness of outline due to good focusing
– out of focus : not in focus