amygdaloid

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A volcanic rock containing many amygdules.
• adjective Shaped like an almond.
• adjective Anatomy Of or relating to the amygdala.
• adjective Resembling a volcanic rock that contains many amygdules.

from The Century Dictionary.

• Almond-shaped.
• Pertaining to or resembling amygdaloid.
• Pertaining to the amygdalæ; tonsilar.
• noun The name given by geologists to igneous rocks or lavas of various composition, of which the most obvious external feature is that they have an amygdaloidal structure. (See amygdaloidal.)

from the GNU version of the Collaborative International Dictionary of English.

• noun (Min.) A variety of trap or basaltic rock, containing small cavities, occupied, wholly or in part, by nodules or geodes of different minerals, esp. agates, quartz, calcite, and the zeolites. When the imbedded minerals are detached or removed by decomposition, it is porous, like lava.
• adjective Almond-shaped.
• adjective Pertaining to, or having the nature of, the rock amygdaloid.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• adjective Shaped like an almond.
• noun A variety of trap or basaltic rock, containing small cavities, occupied, wholly or in part, by nodules or geodes of different minerals, especially agates, quartz, calcite, and the zeolites. When the imbedded minerals are detached or removed by decomposition, it is porous, like lava.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun volcanic rock in which rounded cavities formed by expanding gas have subsequently become filled with mineral deposits
• adjective shaped like an almond