Lewis & Short

oxymĕli, ĭtis, and oxymel, mellis, n., = ὀξύμελι, vinegar-honey, a mixture of vinegar and honey, oxymel, Plin. 23, 2, 29, § 60.
Also written oxymelli: brassica ex aceto oxymelli et sale sparsā (al. oxymelle, al. oxymela), Cato, R. R. 157; Col. 12, 58, 3.