英和和英

語源

Borrowed from Latin focus (“hearth, fireplace”); see there for more. Related to fuel.

Kepler introduced the term into mathematics and the sciences in describing elliptical orbits of planets (quote from Nicholas Mee) : "One of the interesting properties of an ellipse is that if there were a light bulb at one focus, then all the light that it emits would reflect off the ellipse and converge at the other focus. This is why Kepler originally used the name focus for these points."

発音

• (Received Pronunciation) IPA: /ˈfəʊ̯.kəs/, /ˈfɵ̞ʊ̯.kəs/
• (General American, Standard Canadian) IPA: /ˈfoʊ̯.kəs/, /ˈfɔʊ̯.kəs/
• (General Australian, New Zealand) IPA: /ˈfəʉ.kəs/, /ˈfɐ̝ʉ.kəs/
• 韻: -əʊkəs
• ハイフネーション: fo‧cus

名詞

focus (countable and uncountable, plural foci or focuses or focusses)

1. (countable, optics) A point at which reflected or refracted rays of light converge.

   Synonym: focal point

   The heat of sunlight at the focus of a magnifying glass can easily set dry leaves on fire.

2. (countable, geometry) A point of a conic at which rays reflected from a curve or surface converge.
3. (uncountable, photography, cinematography) The fact of the convergence of light on the photographic medium.

   Unfortunately, the license plate is out of focus in this image.

   • 2013 July-August, Catherine Clabby, “Focus on Everything”, in American Scientist:

     Not long ago, it was difficult to produce photographs of tiny creatures with every part in focus. […] A photo processing technique called focus stacking has changed that. Developed as a tool to electronically combine the sharpest bits of multiple digital images, focus stacking is a boon to biologists seeking full focus on a micron scale.

4. (uncountable, photography, cinematography) The quality of the convergence of light on the photographic medium.

   During this scene, the boy’s face shifts subtly from soft focus into sharp focus.

5. (uncountable) Concentration of attention.

   I believe I can bring the high degree of focus required for this important job.

6. (countable) Something to which activity, attention or interest is primarily directed.

   Synonym: focal point

   My studies are my main focus right now.

7. (countable, seismology) The exact point of where an earthquake occurs, in three dimensions (underneath the epicentre).

   The earthquake's focus was at exactly 37 degrees north, 18 degrees south, seventy five meters below the ground.

8. (graphical user interface) The status of being the currently active element in a user interface, often indicated by a visual highlight.

   Text entered at the keyboard or pasted from a clipboard is sent to the component which currently has the focus.

9. (linguistics) The most important word or phrase in a sentence or passage, or the one that imparts information.
10. An object used in casting a magic spell.
    • 2004, Marian Singer, Trish MacGregor, The Only Wiccan Spell Book You'll Ever Need:

      Candles, in fact, are an essential ingredient in many spells. They can be used as either the focus of the spell or as a component that sets the spell's overall mood and tone.

11. (ichthyology) The centre of an older fish's scale, which is the point where a younger fish's scale starts to grow from.

    Coordinate terms: annulus, circulus

使用する際の注意点

The plural "foci" is used in mathematical context, see sense 2 of this noun.

派生語

動詞

focus (third-person singular simple present focuses or focusses, present participle focusing or focussing, simple past and past participle focused or focussed)

1. (transitive) To cause (rays of light, etc) to converge at a single point.
   • 1961 February, “Talking of Trains: Collision at Newcastle”, in Trains Illustrated, pages 75–76:

     The difficulties of focussing colour-light signals on curved tracks to ensure maximum sighting distance were underlined in the recent official report [...] on a low-speed collision at Newcastle Central on July 25, 1960, between an unfitted freight and a diesel-hauled passenger train.

2. (transitive, optics) To adjust (a lens, an optical instrument) in order to position an image with respect to the focal plane.

   You'll need to focus the microscope carefully in order to capture the full detail of this surface.

3. (intransitive, optics, of a lens, optical instrument, etc.) To adjust itself or be adjusted such that light from a scene converges appropriately to create a clear image.

   I can't get the lens to focus.

   The camera focuses automatically on the subject's eyes.

4. (transitive) To direct attention, effort, or energy to a particular audience or task.

   The president focused her remarks on the newcomers.

5. (intransitive) To concentrate one’s attention.

   If you're going to beat your competitors, you need to focus.

6. (intransitive, followed by on or upon) To concentrate one's attention on something; to have as one's central point of interest, concern, etc.

   I have to focus on my work.

7. (computing, graphical user interface, transitive) To transfer the input focus to (a visual element), so that it receives subsequent input.

   The text box won't receive the user's keystrokes unless you explicitly focus it.

8. (accounting, formerly) To aggregate figures of accounts.
   • 1897, Bram Stoker, Dracula, published 1993, page 67:

     Whole pages of it are filled with masses of figures, generally single numbers added up in batches, and then the totals added in batches again, as though he were "focusing" some account, as the auditors put it.

使用する際の注意点

The spellings with -ss- are more common in Commonwealth English than in American English, but in both varieties they are less common than the spellings focuses, focusing, focused.

派生語

関連する語

参照

アナグラム

• Fusco

発音

• (Classical Latin) IPA: [ˈfɔ.kʊs]
• (modern Italianate Ecclesiastical) IPA: [ˈfɔː.kus]

名詞

focus m (genitive focī); second declension

1. fireplace, hearth
2. firepan, coal pan, brazier
3. altar
4. (figuratively) house, family
5. (Late Latin) fire

語形変化

Second-declension noun, with locative.

Locative used in the sense "by the hearth".

同意語

• (fire): ignis

派生語

関連する語

• focillare
• foculare

派生した語

Borrowings:

参照

Further reading

• “focus”, in Charlton T. Lewis and Charles Short (1879), A Latin Dictionary, Oxford: Clarendon Press
• “focus”, in Charlton T. Lewis (1891), An Elementary Latin Dictionary, New York: Harper & Brothers
• "focus", in Charles du Fresne du Cange, Glossarium Mediæ et Infimæ Latinitatis (augmented edition with additions by D. P. Carpenterius, Adelungius and others, edited by Léopold Favre, 1883–1887)
• “focus”, in Gaffiot, Félix (1934), Dictionnaire illustré latin-français, Hachette.
• Carl Meißner; Henry William Auden (1894), Latin Phrase-Book‎, London: Macmillan and Co.
  • to fight for hearth and home: pro aris et focis pugnare, certare, dimicare
    
• “focus”, in Harry Thurston Peck, editor (1898), Harper’s Dictionary of Classical Antiquities, New York: Harper & Brothers
• “focus”, in William Smith et al., editor (1890), A Dictionary of Greek and Roman Antiquities, London: William Wayte. G. E. Marindin