Definition of "startup"

startup¹

/ˈstɑɹtˌʌp/

noun
countable and uncountable, plural startups
1. The act or process of starting a process or machine.
2. A new company or organization or business venture designed for rapid growth.
  Quotations
  Since the launch early last year of Udacity and Coursera, two Silicon Valley start-ups offering free education through MOOCs, massive open online courses, the ivory towers of academia have been shaken to their foundations. University brands built in some cases over centuries have been forced to contemplate the possibility that information technology will rapidly make their existing business model obsolete.
  2013 July 20, “The attack of the MOOCs”, in The Economist, volume 408, number 8845
3. (computing, often capitalized) A folder (especially in Windows), containing shortcuts of applications or programs that start up automatically after a user signs in.
  Quotations
  3. With the file location open, press the Windows logo key + R, type shell:startup, then select OK. This opens the Startup folder. / 4. Copy and paste the shortcut to the app from the file location to the Startup folder.
  Add an app to run automatically at startup in Windows 10, Microsoft Support

startup²

/ˈstɑːtəp/

noun
plural startups
1. (obsolete, dialect, chiefly in the plural) A kind of high-low or thigh-high boot worn by rustic people.
  Quotations
  Galage) a startuppe or clownish shoe.
  1579, Edmund Spenser, The Shepheardes Calender, London: Hugh Singleton, “Februarie,” Glosse
  But Hob and Iohn of the countrey they stept in churlishly, in their high startvps […]
  1592, Robert Greene, A Quip for an Upstart Courtier‎, London: John Wolfe
  When not a Shepheard any thing that could, / But greaz’d his start-ups blacke as Autumns Sloe,
  1619, Michael Drayton, “The Ninth Eglogue” in Pastorals. Contayning Eglogves, With the Man in the Moone, London: John Smethwicke, reproduced in J. William Hebel (ed.), The Works of Michael Drayton, Oxford: Basil Blackwell, 1932, p. 564
2. (obsolete, dialect, chiefly in the plural) A kind of gaiter or legging.
3. (obsolete) One who comes suddenly into notice; an upstart.
  Quotations
  That young start-up hath all the glory of my overthrow: if I can cross him any way, I bless myself every way.
  1598–1599 (first performance), William Shakespeare, “Much Adoe about Nothing”, in Mr. William Shakespeares Comedies, Histories, & Tragedies […] (First Folio), London: […] Isaac Iaggard, and Ed[ward] Blount, published 1623, [Act I, scene iii]