a. [f. FUNCTION sb. + -AL.]
1. Of or pertaining to some function or office; official. In weaker sense: Formal.
1631. J. Burges, Answ. Rejoined, 205. The title of holines is not alwaies personall, but often functionall … thus … the Levites and Priests … were stiled holy.
1860. S. Wilberforce, Addr. Ordin., 23. The validity … of … functional acts … is not affected by the unworthiness of the appointed agent.
1874. H. R. Reynolds, John Bapt., v. § 3. 351. Though He was the God-Man, He had certain national and dispensational offices to fill, for which He needed specific and functional introduction.
1889. Pall Mall G., 23 May, 5/1. Some … functional speeches followed.
2. Phys. a. Of or pertaining to the functions of an organ. Of diseases: Affecting the functions only, not structural or organic. b. Of an organ: Serving a function (opposed to rudimentary).
1843. Sir C. Scudamore, Med. Visit Gräfenberg, 53. It seems probable that more than functional error in the membranes of the brain and spinal marrow exists in this case.
1872. Darwin, Emotions, vi. 164. It would appear … that the lachrymal glands do not … come to full functional activity at a very early period of life.
1874. Maudsley, Respons. in Ment. Dis., ii. 44. It is with so-called functional diseases such as epilepsy, chorea, neuralgia.
1884. Cassell’s Family Mag., Feb., 143/2. Functional disease of the heart.
transf. 1864. Reader, 24 Dec., 792/2. The stage never needed a tonic more. There are many indications of returning health, amid all its symptoms of weakness and functional derangement.
1875. Blake, Zool., 25. They [hoofs] may be either two, as in the Giraffe, four, as in the Hippopotamus, or two functional and two rudimental, as in the greatest number of ruminant types.
1879. Sir G. G. Scott, Lect. Archit., II. 190. My last lecture brought the subject of vaulting to its full functional development,—that which contains all elements whose origin can be traced to the demands of utility, but none which have been introduced purely for decorative purposes.
3. Math. Of or pertaining to a function: see FUNCTION sb. 6.
1806. Gompertz, in Phil. Trans., XCVI. 176. This theorem evidently supposes that the functional values of pz are distinct in the general expression for the sum of the series.
1815. Babbage, Ibid., CV. II. 390. A functional equation is said to be of the first order, when it contains only the first function of the unknown quantity. Ibid., α, β, γ, &c. are known functional characteristics.
1860. Boole, Finite Diff., xi. 218. The most general definition of a functional equation is that it expresses a relation arising from the forms of functions; a relation therefore which is independent of the particular values of the subject variable.
Hence Functionality, functional character; in Math., the condition of being a function. Functionalize v., to place or assign to some function or office (Webster, 1864).
1871. Earle, Philol. Eng. Tongue, § 252. The old native Latin, whose vitality and functionality was all but purely inflectional, springs out of its Greek disguise every now and then, and shows what it can do by its own natural armour.
1879. Cayley, in Encycl. Brit., IX. 818/1. Functionality in Analysis is dependence on a variable or variables.
