quasiperiodicadj.
/ˌkweɪzʌɪpɪərɪˈɒdɪk/, /ˌkwɑːzɪpɪərɪˈɒdɪk/, U.S. /ˌkwɑziˌpɪriˈɑdɪk/, /ˌkweɪzaɪˌpɪriˈɑdɪk/ 1. Chiefly Science. Almost or approximately periodic.
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1871 F. E. Anstie Neuralgia ii. x. 274 Pains of abdominal irritation..may even recur in such a quasi-periodic manner as to strongly suggest the idea of neuralgia in the lumbo-abdominal nerve.
1907 Proc. Physical Soc. 21 396 What, then, would be the result of periodic or quasi-periodic fluctuations of the ætherial pressure?
1949 M. Born Nat. Philos. Cause & Chance vi. 58 A theorem of the great French mathematician Henri Poincaré..states that every mechanical system is, if not exactly periodic, at least quasiperiodic.
2000 R. B. Dunbar in R. J. McIntosh et al. Way Wind Blows ii. 60 ENSO has influenced climate in both the tropics and extratropics since at least the mid-Holocene and produces quasi-periodic climate anomalies.
2. Mathematics. Of a function: such that increasing the variable by a certain fixed amount multiplies the value of the function by a fixed function, or increases it additively by a fixed function.
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1886 Messenger Math. 15 92 Jacobi's Zeta-function..is periodic with respect to 2K, but only quasi-periodic with respect to 2iK'.
1922 Ann. Math. 24 88 It follows that Q(t) is a uniformly continuous quasi-periodic function with the same periods.
1972 T. H. Southard in M. Abramowitz & I. A. Stegun Handbk. Math. Tables xviii. 629 Weierstrass' ζ-function ζ(z) = ζ(z|w, w')... ζ(z) is not an elliptic function, since it is not periodic. However, it is quasi-periodic.
1998 SIAM Jrnl. Numerical Anal. 35 2062 Θ is a quasiperiodic function of ω, a sum of trigonometric functions of period π/β.
3. Physics. Of a motion, oscillation, etc.: having two periods incommensurable in duration.
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1923 Proc. Royal Soc. A. 103 97 These quasi-periodic atmospherics showed considerable diversity of form, the most frequently recurring form was..similar to a uniformly damped sinusoid.
1962 W. B. Thompson Introd. Plasma Physics vii. 164 The orbit of particles along the magnetic field lines is also quasi-periodic, and again an adiabatic invariant may be formed.
2001 A. Medio & M. Lines Nonlinear Dynamics iv. 128 Quasiperiodic orbits can look quite complicated, especially if there exist many incommensurable frequencies.
4. Crystallography and Mathematics. Of a pattern, crystal lattice, etc.: such that any element recurs elsewhere, but at irregular intervals. Cf. quasicrystal n.
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1966 Physical Rev. 147 420/1 The appearance of satellites is interpreted by models which involve a quasiperiodic local order in the alloy.
1987 Science 30 Oct. 660/1 Theoretical efforts have focused on the wide variety of distinct quasiperiodic tiling..that can yield long-range icosahedral order.
1992 Economist 22 Aug. 75/3 Ordinary crystals are the quintessence of symmetry, right down to the atomic level. Quasi-periodic crystals look regular but aren't.
1999 I. Kostov & R. I. Kostov Crystal Habits Minerals iii. 47 Stable quasi-periodic crystals of approximate composition Al6CuLi3 and GaMg2Zn3 have been reported.
Derivatives
ˌquasiperiˈodically adv.
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1964 Electroencephalogr. & Clin. Neurophysiol. 17 192/1 The PLEDs [= periodic lateralized epileptiform discharges] consisted of sharp wave discharges repeating periodically or quasi-periodically..and separated by intervals of apparent quiescence.
1994 N. H. Farhat et al. in K. Pribram Brain & Self Organization xvii. 407 The neuron alters its behavior and..can fire quasiperiodically, erratically, or in bursts, all depending on the amplitude and frequency of the activation potential.
2004 Jrnl. Geophysical Res. B 109 Art. B03403. 1 The interface between the two layers deforms in large domes moving up and down quasiperiodically.
This entry has been updated (OED Third Edition, December 2007; most recently modified version published online March 2022).
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adj.1871