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[peer-ee-od-ik] /ˌpɪər iˈɒd ɪk/
recurring at intervals of time:
periodic revivals of an interest in handicrafts.
occurring or appearing at regular intervals:
periodic visits by doctors to the village.
repeated at irregular intervals; intermittent:
periodic outbreaks of the disease.
Physics. recurring at equal intervals of time.
Mathematics. (of a function) having a graph that repeats after a fixed interval (period) of the independent variable.
  1. characterized by a series of successive circuits or revolutions, as the motion of a planet or satellite.
  2. of or relating to a period, as of the revolution of a heavenly body.
pertaining to or characterized by rhetorical periods, or periodic sentences.
Origin of periodic1
1635-45; < Latin periodicus < Greek periodikós. See period, -ic
Related forms
periodically, adverb
quasi-periodically, adverb
Can be confused
periodic, periodical.


[pur-ahy-od-ik] /ˌpɜr aɪˈɒd ɪk/
adjective, Chemistry
of or derived from a periodic acid.
1830-40; per- + iodic Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2015.
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Examples from the web for periodic
  • It was an insurance policy, typically on a corporate bond, with periodic premium payments and a fixed term.
  • Hypokalemic periodic paralysis is an inherited disorder that causes occasional episodes of muscle weakness.
  • periodic dips in starlight can be caused by planets that partially eclipse, or transit, their host stars.
  • The various archaeologists on the team have had to take periodic breaks from shoveling and shifting to do interviews.
  • He went to a medical reference site and typed in hypokalemic periodic paralysis and hyperthyroidism.
  • Conducts periodic reviews of existing policies to ensure effective ness.
  • Parliamentarians feed periodic rumours of her imminent dismissal.
  • The observatory is repaired during periodic service calls by a space shuttle.
  • Moisture-loving trees that thrive in moist or wet soils, even tolerate periodic flooding.
  • Most can look forward to full, normal lives, interrupted only by periodic examinations to be sure.
British Dictionary definitions for periodic


happening or recurring at intervals; intermittent
of, relating to, or resembling a period
having or occurring in repeated periods or cycles
Derived Forms
periodically, adverb
periodicity (ˌpɪərɪəˈdɪsɪtɪ) 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
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Word Origin and History for periodic

1640s, from French périodique (14c.), from Latin periodicus, from periodus (see period).

Periodic table in chemistry (1889) is from notion of the arrangement, in which similar properties recur at intervals in elements in the same area as you read down the rows of the table. This sense of the word is attested from 1872 (periodic law).

Online Etymology Dictionary, © 2010 Douglas Harper
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periodic in Medicine

periodic pe·ri·od·ic (pĭr'ē-ŏd'ĭk)

  1. Having or marked by repeated cycles.

  2. Recurring at regular intervals.

The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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