Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
mĭnistrātor, ōris, m. [ministro], an attendant, waiter, servant (class.): (turbam) transeo ministratorum, per quos, signo dato, ad inferendam cenam discurritur, Sen. Ep. 95, 24: vinum dominicum ministratoris gratia est, cup-bearer, Petr. 31, 2; Dig. 50, 16, 203: MERCVRIVS, Inscr. Fabr. 114: accensos ministratores, Cato esse scribit, Varr. L. L. 7, § 18 Müll.: cum auriganti Caio ministratorem exhiberet, play the assistant, the instructor, Suet. Vit. 17: cum te ipsum, Sulpici, objurgabam, quod ministratorem peteres, non adversarium, Cic. de Or. 2, 75, 305: quasi ministrator, aderat, subiciens, quid dicerem, id. Fl. 22, 53.