rheid
/ˈriːɪd/Chiefly Geology
noun
A substance which deforms by viscous flow when below its melting point; especially a rock of this kind.
adjective
Characteristic of a rheid.
Origin
1950s. From ancient Greek ῥεῖν to flow (from the same Indo-European base as Sanskrit sru- to flow) + -id, after fluid, liquid.