What is the meaning of focus?

noun

• The concentration of attention or energy on something.
  • usage: "the focus of activity shifted to molecular biology"; "he had no direction in his life"
  • synonyms: focusing, focussing, focal point, direction, centering
• Maximum clarity or distinctness of an image rendered by an optical system.
  • usage: "in focus"; "out of focus"
• Maximum clarity or distinctness of an idea.
  • usage: "the controversy brought clearly into focus an important difference of opinion"
• A central point or locus of an infection in an organism.
  • usage: "the focus of infection"
  • synonyms: focal point, nidus
• Special emphasis attached to something.
  • usage: "the stress was more on accuracy than on speed"
  • synonyms: stress
• A point of convergence of light (or other radiation) or a point from which it diverges.
  • synonyms: focal point
• A fixed reference point on the concave side of a conic section.

verb

• Direct one's attention on something.
  • usage: "Please focus on your studies and not on your hobbies"
  • synonyms: concentrate, center, centre, pore, rivet
• Cause to converge on or toward a central point.
  • usage: "Focus the light on this image"
• Bring into focus or alignment; to converge or cause to converge; of ideas or emotions.
  • synonyms: concenter, concentre, focalize, focalise
• Become focussed or come into focus.
  • usage: "The light focused"
  • synonyms: focalize, focalise
• Put (an image) into focus.
  • usage: "Please focus the image; we cannot enjoy the movie"
  • synonyms: focalize, focalise, sharpen