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

  • adj. Having or marked by repeated cycles.
  • adj. Happening or appearing at regular intervals.
  • adj. Recurring or reappearing from time to time; intermittent.
  • adj. Characterized by periodic sentences.

from Wiktionary, Creative Commons Attribution/Share-Alike License

  • adj. Relative to a period or periods.
  • adj. Having repeated cycles.
  • adj. Occurring at regular intervals.
  • adj. Pertaining to the revolution of a celestial object in its orbit.
  • adj. periodical
  • adj. Having a structure characterized by periodic sentences.
  • adj. for which any return to it must occur in multiples of time steps, for some .
  • adj. Of or derived from a periodic acid.

from the GNU version of the Collaborative International Dictionary of English

  • adj. Pertaining to, derived from, or designating, the highest oxygen acid (HIO�) of iodine.
  • adj. Of or pertaining to a period or periods, or to division by periods.
  • adj. Performed in a period, or regular revolution; proceeding in a series of successive circuits.
  • adj. Happening, by revolution, at a stated time; returning regularly, after a certain period of time; acting, happening, or appearing, at fixed intervals; recurring.
  • adj. Of or pertaining to a period; constituting a complete sentence.

from The Century Dictionary and Cyclopedia

  • Pertaining to or of the nature of a period, cycle, or round of years or events.
  • Performed or proceeding in a series of successive circuits or revolutions: as, the periodic motions of the planets round the sun, or of the moon round the earth.
  • Happening or occurring at regularly recurring intervals of time; statedly recurring; as, a periodic publication; the periodic return of a plant's flowering; periodic outbursts; the periodic character of ague; the periodic motion of a vibrating tuniug-fork or musical string.
  • In rhetoric: Of or pertaining to a period or complete sentence; complete in grammatical structure.
  • Noting that form of sentence in which the sense is incomplete or suspended until the end is reached.
  • In mathematics, with values which recur as the value of the independent variable continuously increases.
  • Noting an acid, a substance produced by the interaction of iodine and aqueous perchloric acid, known only in crystals which contain two molecules of water: HIO4.2H2O. Its solution has a strong acid reaction and it forms several distinct series of salts.

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

  • adj. happening or recurring at regular intervals
  • adj. recurring or reappearing from time to time


from Wiktionary, Creative Commons Attribution/Share-Alike License

From French périodique, from Medieval Latin periodicus ("cyclical"), from Latin periodus ("complete sentence, period, circuit"), from Ancient Greek περίοδος (periodos, "cycle, period of time").

from Wiktionary, Creative Commons Attribution/Share-Alike License

per- +‎ iodic


  • The subsequent section focuses on the opportunity to restructure significantly the sequence, number, and duration of prototyping cycles into what we refer to as a periodic pattern of prototyping.

    Managing New Product and Process Development

  • Alcatel-Lucent, the French maker of telephone network equipment, said Thursday that it planned to cut 3.4 percent of its workforce in France by the end of the year as part of what it described as a periodic review of its personnel needs.

    NYT > Home Page

  • No country that presides over a barbarous occupation, has apartheid laws, engages in periodic genocidal rampages, and elects Zionist ultras such as Netanyahu and Avigdor (Death to Arabs) Liebermann to power has the right to point the finger at anyone else.

    Global Voices in English » Israel: Reflections on the Holocaust Memorial Day and Durban II

  • He has particular research interests in periodic limb movements in sleep (PLMS), and has received a mentored patient-oriented research career development award (K23), through the National Center for Research Resources of the National Institutes of Health, entitled "Periodic Limb Movements in Williams Syndrome".

    Sleep disorders research

  • It was like watching a geyser go off, the way it would jet out in periodic rushes.

    Being Critical : Bev Vincent

  • As a long-term periodic non-sleeper, I greeted this news with a "Yes, and?"

    Sharon Glassman: Why Can't Women Sleep? Part II: How to Sleep Well on Sunday Night

  • The FEC requires candidates to disclose their expenditures, including any payments to bloggers, in periodic reports to the government.

    May 2005

  • Levees along the Mississippi have prevented silt from depositing in periodic floods, resulting in subsidence and loss of land throughout the Delta.

    Rebuilding New Orleans? « BuzzMachine

  • Signatories continue to meet in periodic Conferences of the Parties, of which the most significant to date occurred in Kyoto in 1997, when binding emissions reductions for industrialized countries were proposed under an agreement called the Kyoto Protocol.

    Breaking the Global-Warming Gridlock

  • The mental illness is characterized by periodic delusion and disorientation.

    Essential Guide to Business Style and Usage


Log in or sign up to get involved in the conversation. It's quick and easy.

  • Having written it I realise that pronounced could be on it but I searched and it isn't.

    May 2, 2008

  • Someone's got a list somewhere for words that are spelt the same and pronounced differently.

    May 2, 2008

  • PEER ee Odd ick - happening at regular intervals

    PURR eye Odd ick - having iodine substituends for all hydrogen atoms

    May 2, 2008