focus-n; 6 Senses

Sense Number 1: directed attention, emphasis

Commentary: FOCUS[+state][+attention][+directed] [+role][+emphasis]
NOTE: always implies directed attention to some intended focal point (different from Sense 3)

Lately, John's focus does not seem to be on his work.
The firm's focus shifted from expanding market share to cutting costs.
Mary participated in a focus group for a new software application.
The focus of this article was drug use in American high schools.
The focus is on the object, not the subject, in a passive sentence construction.
Nineteenth century female poets is the focus of tonight's lecture.
The marble mantelpiece forms the focus of the living room. (where an observer's attention is drawn)

WordNet 3.0 Sense Numbers: 1, 5

Sense Number 2: the quality of maximum clarity

Commentary: FOCUS[+quality][+clarity][+maximum]
NOTE: occurs often with 'in' or 'out of'

The pictures on this entire role of film are out of focus.
As the man regained consciousness, the faces in the room came into focus.
The debate brought their differences of opinion clearly in focus.

WordNet 3.0 Sense Numbers: 2, 3

Sense Number 3: the center or origin of something

Commentary: FOCUS[+location][+region][+center]
NOTE: does not imply the directed attention of someone (see Sense 1)
NOTE: refers to the independent origin or center of something, not emphasis placed on it (Sense 1)

The doctor determined that the focus of her infection was the inner ear.
The focus of the earthquake was about two miles south of Santa Barbara.

WordNet 3.0 Sense Numbers: 4

Sense Number 4: a convergent single point, e.g, of particles coming together

Commentary: FOCUS[+point][+physical][+convergent][+electron/+photon]

The focus of the light rays coming into his eye was in front of the lens of the eye. (near-sighted)
The instructions describe where the focus of the electron beam should be.

WordNet 3.0 Sense Numbers: 6

Sense Number 5: a reference point on geometric curves, e.g. ellipses

Commentary: FOCUS[+point][+geometric][+reference][+ellipse/+parabola]

Each ellipse is a conic section defined by two foci.
The focus of a parabola is a fixed point inside the parabola.

WordNet 3.0 Sense Numbers: 7

Sense Number 6: a control device that adjusts a lens

Commentary: FOCUS[+device][+control][+lens]

John adjusted the focus of the telescope to bring the moon into sharp view.
The focus on my camera stopped working after I dropped it.

WordNet 0.0 Sense Numbers: 2c