a. [f. TETRAD + -IC. Cf. F. tétradique (in Cotgr.).] Of, pertaining to, or of the nature of a tetrad.
1788. T. Taylor, Proclus (1792), I. 179. The tetradic ternary, and the triadic quaternary.
b. Chem. That is a tetrad; tetravalent.
1868. Fownes’ Chem. (ed. 10), 257.
1872. Watts, Dict. Chem., VI. 237. Carbon, which combines with 4 atoms of hydrogen, is tetratomic, tetradic, or quadrivalent. Ibid. (1877), Fownes’ Chem. (ed. 12), I. 267. With silver … it [oxygen] forms the two oxides, Ag2O and Ag4O, in the latter of which it is tetradic.
c. Anc. Pros. (a) Containing four different metres or rhythms. (b) Composed of groups of systems, each of which contains four unlike systems.
1891. in Cent. Dict.
