Source : Webster's Revised Unabridged Dictionary (1913)

Thyrsoid \Thyr"soid\ (th[~e]r"soid), Thyrsoidal \Thyr*soid"al\
   (th[~e]r*soid"al), a. [Gr. ?; ? thyrsus + ? form, shape: cf.
   F. thyrso["i]de.]
   Having somewhat the form of a thyrsus.