1.  focus(n = noun.cognition) centering, direction, focal point, focusing, focussing - the concentration of attention or energy on something; "the focus of activity shifted to molecular biology"; "he had no direction in his life"
is a kind of absorption, concentration, engrossment, immersion
has particulars: particularism
Derived forms verb focus₁, verb focus₃

2.  focus(n = noun.attribute) - maximum clarity or distinctness of an image rendered by an optical system; "in focus"; "out of focus"
is a kind of distinctness, sharpness
Derived forms verb focus₅, verb focus₂

3.  focus(n = noun.attribute) - maximum clarity or distinctness of an idea; "the controversy brought clearly into focus an important difference of opinion"
is a kind of clarity, clearness, limpidity, lucidity, lucidness, pellucidity
Derived form verb focus₃

4.  focus(n = noun.state) focal point, nidus - a central point or locus of an infection in an organism; "the focus of infection"
is a kind of point
is a part of focal infection

5.  focus(n = noun.state) stress - special emphasis attached to something; "the stress was more on accuracy than on speed"
is a kind of accent, emphasis

6.  focus(n = noun.phenomenon) focal point - a point of convergence of light (or other radiation) or a point from which it diverges;
is a kind of point
Derived forms adjective focal₂, verb focus₄, verb focus₂

7.  focus(n = noun.location) - a fixed reference point on the concave side of a conic section;
is a kind of point
Derived form adjective focal₂

1.  focus(v = verb.cognition) center, centre, concentrate, pore, rivet - direct one's attention on something; "Please focus on your studies and not on your hobbies"
is one way to cerebrate, cogitate, think
Derived forms noun focus₁, noun focusing₁, noun focussing₁
Sample sentences: Somebody ----s on something

2.  focus(v = verb.perception) - cause to converge on or toward a central point; "Focus the light on this image"
is one way to sharpen
Antonym: blur
Derived forms noun focus₂, noun focus₆, noun focusing₂
Sample sentences: Somebody ----s something; Something ----s something

3.  focus(v = verb.cognition) concenter, concentre, focalise, focalize - bring into focus or alignment; to converge or cause to converge; of ideas or emotions;
is one way to adjust, align, aline, line up
Derived forms noun focus₃, noun focus₁, noun focusing₂
Sample sentences: Somebody ----s something

4.  focus(v = verb.change) focalise, focalize - become focussed or come into focus; "The light focused"
is one way to adapt, adjust, conform
Antonym: blur
Derived forms noun focus₆, noun focusing₂
Sample sentences: Something ----s; Somebody ----s PP

5.  focus(v = verb.change) focalise, focalize, sharpen - put (an image) into focus; "Please focus the image; we cannot enjoy the movie"
is one way to adjust, correct, set
Antonym: blur
Derived forms noun focus₂, noun focusing₂
Sample sentences: Somebody ----s something; Something ----s something; Somebody ----s something PP

1.  A point in which the rays of light meet, after being reflected or refracted, and at which the image is formed; as, the focus of a lens or mirror. [1913 Webster]

2.  A point so related to a conic section and certain straight line called the directrix that the ratio of the distance between any point of the curve and the focus to the distance of the same point from the directrix is constant. [1913 Webster]
" Thus, in the ellipse FGHKLM, A is the focus and CD the directrix, when the ratios FA:FE, GA:GD, MA:MC, etc., are all equal. So in the hyperbola, A is the focus and CD the directrix when the ratio HA:HK is constant for all points of the curve; and in the parabola, A is the focus and CD the directrix when the ratio BA:BC is constant. In the ellipse this ratio is less than unity, in the parabola equal to unity, and in the hyperbola greater than unity. The ellipse and hyperbola have each two foci, and two corresponding directrixes, and the parabola has one focus and one directrix. In the ellipse the sum of the two lines from any point of the curve to the two foci is constant; that is: AG + GB = AH + HB; and in the hyperbola the difference of the corresponding lines is constant. The diameter which passes through the foci of the ellipse is the major axis. The diameter which being produced passes through the foci of the hyperbola is the transverse axis. The middle point of the major or the transverse axis is the center of the curve. Certain other curves, as the lemniscate and the Cartesian ovals, have points called foci, possessing properties similar to those of the foci of conic sections. In an ellipse, rays of light coming from one focus, and reflected from the curve, proceed in lines directed toward the other; in an hyperbola, in lines directed from the other; in a parabola, rays from the focus, after reflection at the curve, proceed in lines parallel to the axis. Thus rays from A in the ellipse are reflected to B; rays from A in the hyperbola are reflected toward L and M away from B." [1913 Webster]

3.  A central point; a point of concentration. [1913 Webster]

   To bring to a focus; to focalize; as, to focus a camera. R. Hunt. [1913 Webster]

focus, n. & v.
--n. (pl. focuses or foci)
1 Physics a the point at which rays or waves meet after reflection or refraction. b the point from which diverging rays or waves appear to proceed. Also called focal point.
2 a Optics the point at which an object must be situated for an image of it given by a lens or mirror to be well defined (bring into focus). b the adjustment of the eye or a lens necessary to produce a clear image (the binoculars were not in focus). c a state of clear definition (the photograph was out of focus).
3 the centre of interest or activity (focus of attention).
4 Geom. one of the points from which the distances to any point of a given curve are connected by a linear relation.
5 Med. the principal site of an infection or other disease.
6 Geol. the place of origin of an earthquake.
--v. (focused, focusing or focussed, focussing)
1 tr. bring into focus.
2 tr. adjust the focus of (a lens, the eye, etc.).
3 tr. & intr. (often foll. by on) concentrate or be concentrated on.
4 intr. & tr. converge or make converge to a focus.

Derivative:
focuser n.

Etymology:
L, = hearth

N  focus, point of convergence, corradiation, center, gathering place, resort haunt retreat, venue, rendezvous, rallying point, headquarters, home, club, depot, trysting place, place of meeting, place of resort, place of assignation, point de reunion, issue.

N  centrality, centricalness, center, middle, focus, core, kernel, nucleus, nucleolus, heart, pole axis, bull's eye, nave, navel, umbilicus, backbone, marrow, pith, vertebra, vertebral column, hotbed, concentration, centralization, symmetry, center of gravity, center of pressure, center of percussion, center of oscillation, center of buoyancy, metacenter, central, centrical, middle, azygous, axial, focal, umbilical, concentric, middlemost, rachidian, spinal, vertebral, middle, midst, centrally.

N  furnace, stove, kiln, oven, cracker, hearth, focus, combustion chamber, athanor, hypocaust, reverberatory, volcano, forge, fiery furnace, limekiln, Dutch oven, tuyere, brasier, salamander, heater, warming pan, boiler, caldron, seething caldron, pot, urn, kettle, chafing-dish, retort, crucible, alembic, still, waffle irons, muffle furnace, induction furnace, electric heater, electric furnace, electric resistance heat, open-hearth furnace, fireplace, gas fireplace, coal fire, wood fire, fire-dog, fire- irons, grate, range, kitchener, caboose, camboose, poker, tongs, shovel, ashpan, hob, trivet, andiron, gridiron, ashdrop, frying-pan, stew-pan, backlog, hearth, inglenook, oil burner, gas burner, Franklin stove, pot-bellied stove, wood-burning stove, central heating, steam heat, hot water heat, gas heat, forced hot air, electric heat, heat pump, solar heat, convective heat, hothouse, bakehouse, washhouse, laundry, conservatory, sudatory, Turkish bath, Russian bath, vapor bath, steam bath, sauna, warm bath, vaporarium.

focus on, out of focus