from The American Heritage® Dictionary of the English Language, 4th Edition

  • adj. Occurring or completed without perceptible delay: Relief was instantaneous.
  • adj. Done or made as quickly or directly as possible: an instantaneous reply to my letter.
  • adj. Present or occurring at a specific instant: instantaneous velocity; instantaneous pressure.

from Wiktionary, Creative Commons Attribution/Share-Alike License

  • adj. Occurring, arising, or functioning without any delay; happening within an imperceptibly brief period of time.

from the GNU version of the Collaborative International Dictionary of English

  • adj. Done or occurring in an instant, or without any perceptible duration of time.
  • adj. At or during a given instant

from The Century Dictionary and Cyclopedia

  • Done or produced in an instant; occurring or acting without any perceptible lapse of time.
  • In mech., existing in or referring to an instant of time; momentary: as, instantaneous position, displacement, velocity, acceleration, etc. (that is, the position, etc., at any instant).

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

  • adj. occurring with no delay


From Medieval Latin īnstantāneus, from Latin īnstāns, īnstant-, present; see instant.
(American Heritage® Dictionary of the English Language, Fourth Edition)
New Latin, 17th century (Wiktionary)



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