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REFERENCE

periodic

adj.
US //ˌpɪɹiˈɑdɪk// pe·ri·od·ic
  1. 1 at regular intervals (adj.)
    B2 Upper Intermediate

    happening again and again at regular times.

    occurring or appearing at regular intervals of time.

    Example

    The machine requires periodic maintenance to keep it running smoothly.

    Example

    The company conducts periodic reviews of its safety protocols to ensure they remain compliant with the latest industry regulations.

  2. 2 repeating cycles (adj.)
    C1 Advanced Technical Science

    having a pattern that repeats itself exactly over time.

    having a structure or behavior characterized by repeated cycles or periods.

    Example

    The ocean tides are a periodic movement caused by the moon.

    Example

    The researcher observed a periodic fluctuation in the data, suggesting that the chemical reaction followed a predictable cycle every four hours.

    • aperiodic
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  1. 3 planetary orbits (adj.)
    C2 Proficiency Technical Astronomy

    relating to the time it takes for a planet or moon to complete one circle.

    pertaining to the time taken for a celestial object to complete one full revolution in its orbit.

    Example

    Comets have periodic orbits that bring them near Earth every few decades.

    Example

    The periodic motion of the planets was first accurately described using elliptical models rather than perfect circles.

  2. 4 chemical acid (adj.)
    C2 Proficiency Technical Science

    relating to a specific type of acid that contains iodine.

    relating to or derived from an acid of iodine in its highest oxidation state.

    Example

    The teacher explained how periodic acid is used in some laboratory tests.

    Example

    The technician prepared a solution of periodic acid to act as an oxidizing agent in the histological staining process.

    Usage

    Pronounced /ˌpɜːraɪˈɒdɪk/ (per-iodic) unlike the common word /ˌpɪəriˈɒdɪk/.

Etymology 1

From French périodique, from Medieval Latin periodicus (“cyclical”), from Latin periodus (“complete sentence, period, circuit”), from Ancient Greek περίοδος (períodos, “cycle, period of time”). By surface analysis, period + -ic.

Etymology 2

From per- + iodic.

Word family

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