Also 6–7 -ade. [f. L. triad-, stem of trias, a. Gr. τριάς, τριαδ-, a group of three. Cf. F. triade (1564 in Hatz.-Darm.).]
1. A group or set of three (persons, things, words, attributes, etc.); three collectively or in connection.
1546. St. Papers Hen. VIII., XI. 341. Two thynges I noted in thEmperour, diligent herynge of me, and good wordys; yf deadis shal nowe folowe accordingely, the triade shall be perfecte.
1614. T. Adams, Divell’s Banket, 28. Sometimes they daunce in Triades, by threes.
a. 1774. Tucker, Lt. Nat. (1834), II. 228. Descend, celestial Graces, sacred Triad.
1862. Merivale, Rom. Emp., VI. liii. 128. The triad of matricides, Nero, Orestes, Alcmæon.
1898. J. T. Fowler, Durham Cath., 49. Three triads of Lancet windows.
b. The number three (in Pythagorean philosophy).
1660. Stanley, Hist. Philos., IX. (1701), 381/1. The Triad is the first number, actually odd, and the first perfect number, and middle, and proportion.
1875. Jowett, Plato (ed. 2), I. 485. The triad or number three is uneven.
2. Specific uses. a. Applied to the Trinity. (repr. Gr. τριάς trinity, used by Theophilus of Antioch and Clement of Alexandria, a. 200.)
1661. Bp. G. Rust, Origen & Opin., 19. There is nothing in that blessed Triad he describes which can be called Creature.
1721. Bailey, Triad … the Trinity.
1806. T. Maurice, Fall of Mogul, I. ii. Divine, ineffable, eternal triad!
1909. H. B. Swete, Holy Spirit in N. T., II. i. 124. [What] He [Jesus] had taught concerning these Three Persons by presenting Them as at once a Triad and a Unity.
b. A group of three associated or correlated deities, beings, or powers.
a. 1746. Holdsworth, Rem. Virgil (1768), 83. Virgil … means the great Triad of deities first received all over the East.
1813. Prichard, Phys. Hist. Man, vii. § 6. 394. We see the attributes of the three persons of the Triad, united in one figure, which represents the supreme Deity, holding conjoined the characters of Creator, Preserver, and Destroyer.
1907. Illingworth, Doctr. Trinity, vii. 130. The many artificially arranged triads,… like that of Brahma, Siva, and Vishnu in India.
c. In Welsh literature: A form of composition characterized by an arrangement of subjects or statements in groups of three.
[1611. Speed, Hist. Gt. Brit., VI. liv. § 12. 189. The Booke Triades mentioned by the Author of the Reformed History of Great Britaine.]
1852. Miss Yonge, Cameos (1877), I. xxxii. 274. Instructions were still oral, and for convenience of memory were drawn up in triads, or verses of three.
1868. Skene, Four Anc. Bks. Wales, I. 28. As early as the date of the Black Book of Caermarthen some of the Welsh traditions appear under the form of short triads, and that MS. contains a fragment of what were probably the earliest—the Triads of the Horses.
d. Mus. A chord of three notes, consisting of a given note with the third and fifth above it; e.g., a common chord (without the octave).
The third may be major or minor, the fifth perfect, augmented, or diminished; hence the triad is described by these adjs. accordingly.
1801. in Busby, Dict. Mus.
1881. Broadhouse, Mus. Acoustics, xv. 320. There are within the octave only three triads or chords of three notes which are consonant.
1889. Prout, Harmony, viii. § 181. A chord … containing a major third and an augmented fifth … is called an augmented triad.
e. Chem. A trivalent element or radical, i.e., one which combines with three atoms of hydrogen or other monovalent element or radical.
1865. Reader, 1 April, 372/2. The family of triatomic atoms or triads, consisting of nitrogen and its analogues, gold and boron.
1865–8. Watts, Dict. Chem., III. 964. There are four triad metals properly so called, namely, aluminium, thallium, indium, and gold.
1868. Fownes, Elem. Chem. (ed. 10), 252. Each element is connected with others by a number of lines, or connecting bonds, corresponding to its degree of equivalence; a monad being connected … by only one such bond, a triad by three.
f. Biol. (a) A group of three cells, e.g., spores. (b) A tertiary unit of organization consisting of an aggregate of dyads: cf. DYAD 2 b. Also attrib., as triad-deme: see DEME sb.2 2.
1876. trans. Schützenberger’s Ferment., 52. The two spores connected together have only one plane surface, the triads have two.
1883. [see DEME sb.2 2].
g. Pros. A group of three lines having different rhythms.
1885. [see DYAD 2 c].
h. Math. (a) A set of three things, esp. in Geom. of three points. (b) In Quaternions, An indeterminate product of three vectors.
1850. Cayley, Math. Papers, I. 481. Forming with seven letters … a system of seven triads containing every possible duad.
1885. Leudesdorf, Cremona’s Proj. Geom., 37. If the triad ABC be projected from S upon s1 (giving A1B1C1), and the triad A′B′C′ be projected from S upon s2 (giving A2B2C2); then the triads A1B1C1 and A2B2C2 will be in perspective.
i. Cryst. Triad axis, an axis of trigonal symmetry.
1909. in Cent. Dict. Supp.
3. Triad Society [trans. Chinese San Ho Hui, lit. ‘three unite society,’ i.e., ‘triple union society,’ according to Giles meaning ‘the union of Heaven, Earth, and Man’]. A secret Chinese society, formed in the reign of Yung Chêng, 1723–36, with the alleged purpose of ousting the Manchu dynasty; now having a large membership in Southern China and various foreign countries. Hence Triads = members of the Triad Society.
1821. W. Milne, Acc. Triad Society, in Trans. Royal Asiatic Soc. (1827), I. 240. The name … seems … to be the San hŏ hwuy, i. e. ‘The Society of the Three united, or the Triad Society.’
1836. Sir J. Davis, Chinese, xi. II. 15. The San-hŏ-hoey, or Triad Society…. The name seems to imply that when Heaven, Earth, and Man combine to favour them, they shall succeed in subverting the present Tartar dynasty.
1848. S. W. Williams, Middle Kingd., I. viii. 395. The English government of Hongkong, enacted in 1845, that any Chinese living in that colony who was ascertained to belong to the Triad Society, should be declared guilty of felony, be imprisoned for three years, and after branding expelled the colony.
1900. Daily News, 13 Nov., 9/3. The programme of the Triads.
1907. Daily Chron., 28 May, 1/7. A rebellion has broken out in Kwantung. About 30,000 persons, headed by the Triad Secret Society, have risen.
