Opodeldoc is a popular synonym for soap Liniment (q.v.). The origin of the term, which was apparently applied by Paracelsus to various forms of liniments or local applications, is not known. The opo is the same as the opo of opopanax, opobalsamum, &c., and is doubtless derived from the Greek opos, 'juice.' See Notes and Queries, October 1888, p. 316.
Opodeldoc
Chambers's Encyclopaedia, Volume 7: Maltebrun to Pearson, p. 615
Source scan(s): p. 0628