Lewis & Short

2. quā̆drū̆plātor (quā̆drī̆-), ōris, m. [quadruplor], a public informer, who received a fourth part of the thing informed against (acc. to others, against one who committed an offence punishable with a fourfold penalty; cf. sector); also, in gen., a trickster, chicaner, Plaut. Pers. 1, 2, 18: deterrimus, Cic. Verr. 2, 2, 7, § 21; 2, 2, 8, § 22; Liv. 3, 72; cf. Paul. ex Fest. p. 259, 3 Müll.; Cic. Div. in Caecil. 7, 24; 21, 68.