a. and sb. [f. Gr. κολλο- comb. form of κόλλα glue + -ειδης -form: see -OID.]
A. adj. Of the nature or appearance of glue.
1. Path. Colloid substance, tissue, matter, corpuscles, spheres: a homogeneous or slightly granular gelatinous substance into which the cells are changed in certain forms of degeneration of tissue (colloid degeneration, metamorphosis). Colloid cancer: a form of cancer in which colloid degeneration takes place.
1847–9. Todd, Cycl. Anat., IX. 118/2. A form most distinct in … colloid cancer and fibrous tumours.
1870. T. Holmes, Syst. Surg. (ed. 2), I. 576. A section of the tumour exhibited the simplest colloid structure.
1876. trans. Wagner’s Gen. Pathol., 329. Colloid metamorphosis consists in the transformation of tissues into a completely homogeneous, colorless or faint yellow, dull, translucent, sometimes fluid or soft-like glue … substance.
2. Chem. Applied by Graham, 1861, to describe a peculiar state of aggregation in which substances exist; opposed to crystalloid. Substances in the colloid state are characterized by little or no tendency to diffuse through animal membranes or vegetable parchment, do not readily crystallize, are inert in their chemical relations, but are highly changeable. So called because gelatin may be taken as the type of the class.
1861. T. Graham, in Phil. Trans. (1862), 184, note. Certain liquid colloid substances are capable of forming a jelly and yet still remain liquefiable by heat and soluble in water. Such is gelatine itself.
1862. H. Spencer, First Princ., II. xiii. (1875), § 101. Matter has two solid states, distinguished as crystalloid and colloid; of which the first is due to union of the individual atoms or molecules, and the second to the union of groups of such individual atoms or molecules.
1869. Mrs. Somerville, Molec. Sc., I. iii. 110. Solutions of … crystalloids pass freely through colloid substances, such as parchment … and membrane, into water, though they have no pores.
3. Min. One of the forms in which minerals occur: see quot.
1879. Rutley, Study Rocks, x. 152. This condition as intermediate between the crystallised and the colloid forms of silica.
1885. Geikie, Geol., II. II. ii. 62. Minerals … occur in four conditions, according to the circumstances under which they have been produced. 1. Crystalline.… 2. Vitreous.… 3. Colloid, as a jelly-like though stony substance, deposited from aqueous solution. The most abundant mineral in nature which takes the colloid form is silica…. 4. Amorphous.
B. sb.
1. Path. The colorless or yellowish transparent jelly-like substance formed in colloid degeneration; also a similar substance found normally in the thyroid gland.
1849–52. Todd, Cycl. Anat., IV. 1116/2. But no example of colloid in it [thymus gland] has yet been detected.
1874. Jones & Siev., Pathol. Anat., 126. Colloid is related to the albuminates, and resembles mucin.
2. Chem. (mostly pl.) A colloid body or substance, as distinct from a crystalloid: see A. 2.
1861. T. Graham, in Phil. Trans. (1862), 183 [see COLLOIDAL 1].
1869. Mrs. Somerville, Molec. Sc., I. iii. 109. Substances such as salts, sugars, &c., are much more diffusible than colloids or amorphous sticky bodies, such as gum, caramel, jellies.
1880. Bastian, Brain, i. 5. It is known … that certain typical colloids may, under some conditions, be converted into crystalloids.
