[ in-stuhn-tey-nee-uhs ]
/ ˌɪn stənˈteɪ ni əs /


occurring, done, or completed in an instant: an instantaneous response.
existing at or pertaining to a particular instant: the instantaneous position of the rocket.

Nearby words

  1. instant camera,
  2. instant message,
  3. instant messaging,
  4. instant photography,
  5. instant replay,
  6. instantaneous sound pressure,
  7. instanter,
  8. instantiate,
  9. instantiation,
  10. instantize

Origin of instantaneous

From the Medieval Latin word instantāneus, dating back to 1645–55. See instant, -an, -eous

Related formsin·stan·ta·ne·i·ty [in-stan-tn-ee-i-tee, in-stuhn-tuh-nee-] /ɪnˌstæn tnˈi ɪ ti, ˌɪn stən təˈni-/, in·stan·ta·ne·ous·ness, nounin·stan·ta·ne·ous·ly, adverb Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for instantaneous

British Dictionary definitions for instantaneous


/ (ˌɪnstənˈteɪnɪəs) /


occurring with almost no delay; immediate
happening or completed within a momentinstantaneous death
  1. occurring at or associated with a particular instant
  2. equal to the limit of the average value of a given variable as the time interval over which the variable is considered approaches zeroinstantaneous velocity
Derived Formsinstantaneously, adverbinstantaneousness or instantaneity (ɪnˌstæntəˈniːɪtɪ), noun

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for instantaneous



1640s (implied in instantaneously), formed in English from Medieval Latin *instantaneus, from instantem (see instant (n.)) on model of spontaneous. Related: Instantaneousness.

Online Etymology Dictionary, © 2010 Douglas Harper