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."[1]
Not long ago, it was difficult to produce photographs of tiny creatures with every part infocus.[…]A photo processing technique calledfocus 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 fullfocus on a micron scale.
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 thefocus of the spell or as a component that sets the spell's overall mood and tone.
1961 February, “Talking of Trains: Collision at Newcastle”, inTrains Illustrated, pages75–76:
The difficulties offocussing 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.
You'll need tofocus the microscope carefully in order to capture the full detail of this surface.
(intransitive,optics, of a lens, optical instrument, etc.) Toadjust itself or be adjusted such that light from a scene converges appropriately to create a clear image.
I can't get the lens tofocus.
The camerafocuses automatically on the subject's eyes.
(transitive) To direct attention, effort, or energy to a particular audience or task.
The presidentfocused her remarks on the newcomers.
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.
The spellings with -ss- are more common in Commonwealth English than in American English, but in both varieties they are less common than the spellingsfocuses,focusing,focused.
^Philippa, Marlies,Debrabandere, Frans, Quak, Arend, Schoonheim, Tanneke,van der Sijs, Nicoline (2003–2009)Etymologisch woordenboek van het Nederlands (in Dutch), Amsterdam: Amsterdam University Press
Matasović, and Hamp before him, opt to derive this fromProto-Indo-European*dʰegʷʰ-(“to burn”); Matasović believes that the-c- would have spread from the nominative of a root noun*dʰṓgʷʰ-s (>*dʰṓkʷʰ-s).[1]
^Matasović, Ranko (2010) “The etymology of Latin focus and the devoicing of final stops before *s in Proto-Indo-European”, inHistorische Sprachforschung / Historical Linguistics[1], volume123, Vandenhoeck & Ruprecht,→ISSN,→JSTOR, pages212–216
“focus”, inCharlton T. Lewis and Charles Short (1879)A Latin Dictionary, Oxford: Clarendon Press
“focus”, inCharlton T. Lewis (1891)An Elementary Latin Dictionary, New York: Harper & Brothers
"focus", in Charles du Fresne du Cange’sGlossarium Mediæ et Infimæ Latinitatis (augmented edition with additions by D. P. Carpenterius, Adelungius and others, edited by Léopold Favre, 1883–1887)
Carl Meißner, Henry William Auden (1894)Latin Phrase-Book[2], London:Macmillan and Co.
to fight for hearth and home:pro ariset focis pugnare, certare, dimicare
“focus”, inHarry Thurston Peck, editor (1898),Harper's Dictionary of Classical Antiquities, New York: Harper & Brothers
“focus”, inWilliam Smith et al., editor (1890),A Dictionary of Greek and Roman Antiquities, London: William Wayte. G. E. Marindin
De Vaan, Michiel (2008)Etymological Dictionary of Latin and the other Italic Languages (Leiden Indo-European Etymological Dictionary Series; 7), Leiden, Boston: Brill,→ISBN,pages228-9
