pedialadj.
/ˈpiːdɪəl/, U.S. /ˈpidiəl/ Crystallography.
Relating to or designating a triclinic crystal form having no centre of symmetry. Cf. pinacoidal adj.
ΚΠ
1922 Jrnl. Amer. Chem. Soc. 44 1523 The crystals are certainly triclinic and the occurrence of frequent truncation of one sharp end without a corresponding face at the other end seems to indicate the rather rare pedial symmetry.
1958 Trans. Amer. Math. Soc. 88 177 Except for the pedial class of the triclinic system, there are a number of equivalent ways in which the triad of vectors..may be chosen.
1998 Canad. Mineralogist 36 775 The mineral occurs as..well-formed, hexagonal, short prismatic to tabular crystals with pedial terminations.
This is a new entry (OED Third Edition, September 2005; most recently modified version published online March 2022).
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adj.1922