focus

¹fo·cus

noun \ˈfō-kəs\

plural ; fo·ci \ˈfō-ˌsī also -ˌkī\ (audio pronunciation) (audio pronunciation)also ; fo·cus·es

Definition of FOCUS

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

3

: a localized area of disease or the chief site of a generalized disease or infection