Source : Webster's Revised Unabridged Dictionary (1913)

Amygdaloid \A*myg"da*loid\, n. [Gr. ? almond + -oid: cf. F.
   amygdalo["i]de.] (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.

Amygdaloid \A*myg"da*loid\, Amygdaloidal \A*myg`da*loid"al\, a.
   1. Almond-shaped.

   2. Pertaining to, or having the nature of, the rock
      amygdaloid.

Source : WordNet®

amygdaloid
     adj : shaped like an almond [syn: {almond-shaped}, {amygdaliform},
            {amygdaloidal}]