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▪ I. periodic, a.1|pɪərɪˈɒdɪk|
[a. F. périodique (14th c. in Hatz.-Darm.), ad. L. periodicus (Pliny), a. Gr. περιοδικός coming round at certain intervals, f. περίοδος period: see -ic.]
1. Of, pertaining, or proper to the revolution of a heavenly body in its orbit, as periodic motion, periodic time.
1642Howell For. Trav. (Arb.) 87 In as short a compas of time as the Sun finisheth his periodic annuall motion. 1715tr. Gregory's Astron. I. 192 If the Sun were retained by the same Force [Gravity], propagated so far as itself, the Cubes of the Distances of the Sun and Moon..would have the same Ratio as the Squares of their Periodic Times. 1833Herschel Astron. viii. 248 A direct method of ascertaining the periodic time of each planet.
2. Characterized by periods; recurring at regular intervals; spec. in Path. having regularly recurring symptoms, as periodic fever. Often loosely, Recurring or reappearing at intervals; intermittent.
periodic classification or periodic system (Chem.): an arrangement or classification of the chemical elements according to the periodic law; periodic function (Math.): see period n. 14. periodic inequality (Astron.): see inequality 4. periodic law (Chem.): the statement of the fact (first pointed out by Mendeléeff in 1869) that the properties of the chemical elements are periodic functions of their atomic weights; i.e. that when arranged in the order of these weights, the elements fall into recurring groups or series, so that those having similar chemical and physical properties recur at regular intervals; now recognized to be a function of atomic number rather than of atomic weight, thus removing certain discrepancies in the original scheme; periodic table (Chem.): a table of the elements arranged according to the periodic law; spec. one in which they are arranged in order of atomic number, usu. in rows, such that groups of elements possessing analogous electronic structures, and hence exhibiting similar properties, form vertical columns (‘groups’) of the table.
1661Lovell Hist. Anim. & Min. 365 The boulimos is a great periodick appetite, often ending in nauseousnesse. 1742Young Nt. Th. vi. 154 Periodic Potions for the Sick. 1750H. Walpole Lett. to Mann (1834) II. 328, I have advised several who are going to keep their next earthquake in the country to take the bark for it, as it is so periodic. 1805Med. Jrnl. XIV. 88 The fevers of the periodic class exhibit great variety of condition. 1822–56De Quincey Confess. (1862) 25 The fretting..of anxiety, which..he kept alive by this periodic exaction. 1850J. F. W. Herschel in Phil. Trans. R. Soc. CXL. 400 If Ax, Bx, &c. be simply constant, the function may be termed a periodic one, since it assumes in periodic and constantly recurring succession the values A, B, C..N, A, B, &c. ad infinitum. 1859Parkinson Optics (1866) 104 The cylindrical beams transmitted through these annular lenses sweep the horizon and produce a revolving or periodic light. 1872Phil. Mag. XLIII. 251 The regular progression in physical and chemical properties observable in members of the same family..are either consequences of, or closely related to, these ‘periodic laws’. 1875Chem. News 24 Dec. 293/1 The periodic law indicates the gaps which still exist in the system of the known elements, and enables us to predict the properties of the unknown elements. Ibid. 294/1 These characters of [gallium]..have been obtained..by considering its place in the periodic system of the elements. 1879Cayley Coll. Math. Papers XI. 529 The functions sin u, cos u, are periodic, having the period 2π, sin / cos (u + 2π) = sin / cos (u); and the half-period π, sin / cos (u + π) = - sin / cos u; the periodicity may be verified by means of the foregoing fractional forms. 1880E. Cleminshaw Wurtz' Atom. The. 154 A function of the atomic weights, which function is periodic. 1881Stokes in Nature XXIV. 617/2 A system of any kind subject to periodic disturbing forces. 1881Chem. News 14 Jan. 16/1 The criticism of Prof. Wurtz upon the periodic classification. 1882Minchin Unipl. Kinemat. 13 A function of a variable, x, is said to be a periodic function..if its values repeat themselves for values of the variable differing by a constant. 1895Thomson & Bloxam Bloxam's Chem. (ed. 8) 278 The Periodic Table has found a twofold application. 1913Periodic system [see atomic number s.v. atomic a. 1] 1919Jrnl. Chem. Soc. CXV. 11 The occupant of a separate place in the periodic table of elements. 1930Engineering 21 Mar. 372/2 The sequence of the elements in the old periodic table with its eight groups and seven periods. 1957Periodic table [see lanthanide 1]. 1969J. W. van Spronsen (title) The periodic system of chemical elements. 1974Encycl. Brit. Macropædia IV. 116/2 The periodic classification places elements with similar electron arrangements in vertical columns. 1974Goldberg & Dillard College Chem. ii. 38 The periodic law..states that the properties of the elements are periodic functions of their atomic numbers.
3. Of or pertaining to a rhetorical or grammatical period; characterized by or expressed in periods.
1701tr. Le Clerc's Prim. Fathers (1702) 276 Those Letters are not writ in a Periodick Style, as the Orations. 1840–1De Quincey Rhetoric Wks. 1859 XI. 52 The splendour of his periodic diction, with his fine delivery, compensated his defect in imagery. 1860Marsh Eng. Lang. xvii. 361 The Italian resembles the Latin in independence of fixed laws of periodic arrangement. 1875Jowett Plato (ed. 2) III. 527 Anaxagoras never attained to a connected or periodic style.
4. = periodical a. 5. rare.
1835I. Taylor Spir. Despot. i. 19 The despotism of the Periodic Press. 1904Westm. Gaz. 30 Apr. 5/2 There is in all these respects no better model for the journalist or periodic writer. 1930H. G. Wells Autocracy of Mr. Parham ii. iv. 128 The need of a stronger and clearer guidance in our periodic literature.
5. Relating to a period or space of time. rare.
1884J. Tait Mind in Matter (1892) 168 A periodic conception of the [six] ‘days’ would at once suggest itself,..the divine rest embracing an indefinite period.
6. as n. pl. = periodical n. 3.
1920C. E. Mulford Johnny Nelson xvii. 222 That's th' worst of them periodics! You can't never tell when they'll start.
▪ II. periodic, a.2, per-iodic
see under periodate. |