geode Meaning, Definition & Usage

  1. noun (mineralogy) a hollow rock or nodule with the cavity usually lined with crystals

WordNet

Ge"ode noun
Etymology
F. géode, L. geodes, fr. Gr. earthlike; , , the earth + form.
Definitions
  1. (Min.) (a) A nodule of stone, containing a cavity, lined with crystals or mineral matter. (b) The cavity in such a nodule.

Webster 1913