a. (sb.) [f. TRIAD + -IC.] Of, pertaining to, or constituting a triad; consisting of triads.
1788. T. Taylor, Proclus, I. 123. We shall find a line [to be] monadic; but a superficies dyadic, and a solid body triadic.
1839. Bailey, Festus, viii. (1848), 95. Nature’s great Triadic principle, in all things seen.
1850. Cayley, Math. Papers, I. 481. On the triadic arrangements of seven and fifteen things.
b. Triadic canon (Gr. Ch.): a hymn (CANON1 7 b) in honor of the Trinity.
1862. Neale, Hymns East. Ch., 160. It would be impossible without wearying the reader, to translate the whole of the Triadic Canons.
c. Chem. That is a triad; trivalent.
1882. in Ogilvie (Annandale).
d. Anc. Pros. (a) Containing three different meters or rhythms. (b) Composed of groups of systems, each of which contains three unlike systems.
1891. in Cent. Dict.
e. Of or belonging to the Welsh Triads.
1849. T. Stephens, Lit. Kymry, 447. The Triadic form is frequently seen in the poems of Aneurin, and Llywarch Hen.
1906. C. Squire, Mythol. Anc. Brit., v. 52. We learn … that the battle of Camlan was one of the ‘Three Frivolous Battles of Britain,’… and that the usual ‘Three’ alone escaped from it, though Arthur himself is, in spite of the triadic convention, added as a fourth.
B. sb. Math. In Quaternions, A sum of products of three vectors.
So Triadical a., = triadic; Triadically adv., according to triads, in the manner of a triad (in quot. 1860, in sense 2 c: cf. e above).
1837. Whewell, Hist. Induct. Sc. (1857), I. 223. The intellectual gods produce all things triadically.
1860. J. J. Thomas, Brit. Antiq., 214. The gallant Cymro triadically repeated, with all the glowing pathos and bardic enthusiasm of an inspired patriot, several englynion.
1890. Dublin Rev., Jan., 60, note. A transcript of an old Triadical commentary.
