Source : Webster's Revised Unabridged Dictionary (1913)

Soredia \So*re"di*a\, n.,
   pl. of {Soredium}.

Soredium \So*re"di*um\, n.; pl. {Soredia}. [NL., fr. Gr. ? a
   heap.] (Bot.)
   A patch of granular bodies on the surface of the thallus of
   lichens.