thyrsus(n = noun.plant)thyrse - a dense flower cluster (as of the lilac or horse chestnut) in which the main axis is racemose and the branches are cymose;
A staff entwined with ivy, and surmounted by a pine cone, or by a bunch of vine or ivy leaves with grapes or berries. It is an attribute of Bacchus, and of the satyrs and others engaging in Bacchic rites. [1913 Webster]
A species of inflorescence; a dense panicle, as in the lilac and horse-chestnut. [1913 Webster]
, n. (pl. thyrsi)
1 Gk & Rom. Antiq. a staff tipped with an ornament like a pine-cone, an attribute of Bacchus.
2 Bot. an inflorescence as in lilac, with the primary axis racemose and the secondary axis cymose.