Defrutum, defruti, n. g. pen. cor. Plin. Newe wine sodde vntill the thirde parte be boiled away.Defruta lucosa dulci cœno.Stat. Pinguía defruta. Virg.
Lewis and Short: Latin dictionary
dēfrŭtum, i, n. (perh. for defervitum, sc. mustum), must boiled down (acc. to Varr. and Col., to one third; acc. to Plin., only to one half), Varr. ap. Non. 551, 24; Col. 12, 20 sq.; Plin. 14, 9, 11, 80; Pall. Oct. 18; Plaut. Ps. 2, 4, 51; Verg. G. 4, 269.