• synonyms


noun Petrology.
  1. a volcanic rock in which rounded cavities formed by the expansion of gas or steam have later become filled with deposits of various minerals.
Show More
adjective Also a·myg·da·loi·dal.
  1. (of rocks) containing amygdules.
  2. almond-shaped.
  3. Anatomy. of or relating to an amygdala.
Show More

Origin of amygdaloid

1785–95; < Latin amygdal(a) almond + -oid
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Examples from the Web for amygdaloidal

Historical Examples

  • I ascended one, and found it was capped with trap rock in amygdaloidal nodules.

    Journal of an Expedition into the Interior of Tropical Australia

    Thomas Mitchell

  • Occasionally we meet with igneous rocks which are more or less vesicular and amygdaloidal throughout their entire mass.


    James Geikie

  • It occurs in a series of amygdaloidal dolerites or diabases, and in the associated sandstones and conglomerates.

  • It may be traced for many miles, passing through the amygdaloidal and other traps of the hill called Normans Law.

  • They consist almost exclusively of greenstone, becoming, in a few instances, earthy and amygdaloidal.

British Dictionary definitions for amygdaloidal


  1. (of a volcanic rock) containing amygdales
  2. a less common form of amygdaloid (def. 2)
Show More


  1. a volcanic igneous rock containing amygdales
Show More
  1. having the shape of an almond
  2. a less common form of amygdaloidal (def. 1)
Show More
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

amygdaloidal in Medicine


  1. Shaped like an almond.
  2. Of or relating to an amygdala.
Show More
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.