The Collaborative International Dictionary of English v.0.48:

Euphorbium \Eu*phor"bi*um\, n. [NL., fr. L. euphorbeum, from Gr.
   ?; -- so called after Euphorbus, a Greek physician.] (Med.)
   An inodorous exudation, usually in the form of yellow tears,
   produced chiefly by the African Euphorbia resinifera. It
   was formerly employed medicinally, but was found so violent
   in its effects that its use is nearly abandoned.
   [1913 Webster]

WordNet (r) 3.0 (2006):

euphorbium
    n 1: an acrid brown gum resin now used mainly in veterinary
         medicine [syn: euphorbium, gum eurphorbium]