FOCUSSED
focused, focussed
(adjective) (of light rays) converging on a point; “focused light rays can set something afire”
focused, focussed
(adjective) being in focus or brought into focus
Source: WordNet® 3.1
Adjective
focussed (comparative more focussed, superlative most focussed)
(British) Alternative spelling of focused
Antonyms
• unfocussed
Verb
focussed
(British) simple past tense and past participle of focus
Usage notes
• The spelling focused is much more common in the US but also more common in the UK and Australia.
• Focussed violates the UK spelling rule that calls for a doubling of a final unsupported consonant when a suffix beginning with a vowel is appended, only when the final vowel is both short and accented, (cf no doubling in opened, covered, callused, biased, irises, bonuses), except when the final letter is L, which doubles also when the syllable is unaccented (cf travelled, levelled), and also in some cases where a prefix is added to an established word. But the point is clearly difficult in that the irregular spelling biassed is also occasionally seen.
• The Oxford English Dictionary describes the spelling focussed as irregular.
• The spelling focussed is a widely seen UK spelling but focused, (focuses, focusing) is more common in prestige publications.
• The spelling focussed is nowadays more common in Canada and New Zealand than in the UK.
Source: Wiktionary
FOCUS
Fo"cus, n.; pl. E. Focuses, L. Foci. Etym: [L. focus hearth,
fireplace; perh. akin to E. bake. Cf. Curfew, Fuel, Fusil the
firearm.]
1. (Opt.)
Definition: A point in which the rays of light meet, after being reflected
or refrcted, and at which the image is formed; as, the focus of a
lens or mirror.
2. (Geom.)
Definition: A point so related to a conic section and certain straight line
called the directrix that the ratio of the distace between any point
of the curve and the focus to the distance of the same point from the
directrix is constant.
Note: 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.
3. A central point; a point of concentration. Aplanatic focus. (Opt.)
See under Aplanatic.
– Conjugate focus (Opt.), the focus for rays which have a sensible
divergence, as from a near object; -- so called because the positions
of the object and its image are interchangeable.
– Focus tube (Phys.), a vacuum tube for Roentgen rays in which the
cathode rays are focused upon the anticathode, for intensifying the
effect.
– Principal, or Solar, focus (Opt.), the focus for parallel rays.
Fo"cus, v. t. [imp. & p. p. Focused; p. pr. & vb. n. Focusing.]
Definition: To bring to a focus; to focalize; as, to focus a camera. R.
Hunt.
Source: Webster’s Unabridged Dictionary 1913 Edition