plesiomorphous, a. Cryst.
(ˌpliːsɪəʊˈmɔːfəs)
[f. plesio- + Gr. µορϕή form + -ous.]
Very near in form; crystallizing in forms closely resembling but not identical with each other. So ˌplesioˈmorphic a. in same sense; ˌplesioˈmorphism, the fact or condition of being plesiomorphous.
| 1833 Rep. Brit. Assoc. 1831, 1832 429 Plesiomorphism.—As the differences between the angles of the carbonates and sulphates above quoted cannot be accounted for by any accidental causes.., some crystallographers have been led to reject the term isomorphous as applied to such crystallized compounds, and to substitute in its place the term plesiomorphous. 1837 Whewell Hist. Induct. Sc. III. 222 It has since been proposed to call such groups plesiomorphous. 1845 N. Brit. Rev. II. 314 The term plesiomorphous (nearly of the same shape) is generally substituted. Ibid., Plesiomorphism serves to remove the difficulties. 1850 Daubeny Atom. The. vi. (ed. 2) 175 It has been proposed to employ the term plesiomorphism, where the resemblance between two bodies in external form is not regarded as complete. 1890 Cent. Dict., Plesiomorphic, same as plesiomorphous. |