Source : Webster's Revised Unabridged Dictionary (1913)

Thyrse \Thyrse\ (th[~e]rs), n. [Cf. F. thyrse.]
   A thyrsus.

Source : WordNet®

thyrse
     n : a dense flower cluster (as of the lilac or horse chestnut)
         in which the main axis is racemose and the branches are
         cymose [syn: {thyrsus}]
     [also: {therses} (pl)]