n the concentration of attention or energy on something
n maximum clarity or distinctness of an image rendered by an optical system
n maximum clarity or distinctness of an idea
n a central point or locus of an infection in an organism
n special emphasis attached to something
n a point of convergence of light (or other radiation) or a point from which it diverges
n a fixed reference point on the concave side of a conic section
v direct one's attention on something
v cause to converge on or toward a central point
v bring into focus or alignment; to converge or cause to converge; of ideas or emotions
v become focussed or come into focus
v put (an image) into focus; we cannot enjoy the movie"