Lewis & Short

1. quintus (old form quinctus, Plaut. Trin. 2, 4, 123), a, um, num. adj. [quinque], the fifth: quarta invidia, quinta ambitio, Plaut. Pers. 4, 4, 8: locus, Cic. Inv. 1, 53, 102; 1, 55, 107: natura, id. Tusc. 1, 17, 41: quinta pars, quintessence, essence, Hor. C. 1, 13, 16: quinto mense, quinto die, Liv. 31, 7.
Advv.

  1. A. quintum, for the fifth time: declarati consules Q. Fabius Maximus quintum, Q. Fabius Flaccus quartum, Liv. 27, 6; 6, 42; Vell. 1, 14, 6.
  2. B. quintō, for the fifth time: eodem anno lectisternium Romae, quinto post conditam Urbem, habitum est, Liv. 8, 25.

2. Quintus, i, m., and Quinta, ae, f., Roman prænomen; the former usually abbreviated Q.: Quintus Arrius, Cic. Mil. 17, 46: Q. Scaevola, id. Phil. 8, 10, 31.
Quinta, Cic. Cael. 14, 34; id. Har. Resp. 13, 27; Liv. 29, 14, 12.