thyrsusPronunciation: /ˈθəːsəs/Definition of thyrsus noun (plural thyrsi /-sʌɪ, -siː/) (in ancient Greece and Rome) a staff or spear tipped with an ornament like a pine cone, carried by Bacchus and his followers. Origin:Latin, from Greek thursos 'plant stalk, Bacchic staff'thyrsus in other Oxford dictionaries Definition of thyrsus in the US English dictionary