Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
disceptātor, ōris, m. [discepto], an umpire, arbitrator, judge: disceptator id est rei sententiaeque moderator, Cic. Part. Or. 3, 10: IVRIS DISCEPTATOR, QVI PRIVATA IVDICET IVDICARIVE IVBEAT, PRAETOR ESTO, id. Leg. 3, 3, 8: nec vero quisquam privatus erat disceptator aut arbiter litis, id. Rep. 5, 2; cf. id. Cael. 15; Plaut. Most. 5, 2, 16; Cic. Fl. 38, 97; id. Agr. 1, 7 fin.; id. Fam. 13, 26, 2; * Caes. B. G. 7, 37, 5; Liv. 1, 50; 8, 23; Asin. Pollio ap. Quint. 9, 4, 132 al.