Lewis & Short

armentum, i, n. (old form armenta, ae, f., Liv. Andron. and Enn. ap. Non. p. 190, 20; Enn. ap. Paul. ex Fest. p. 4 Müll.) [contr. for arimentum from aro, Varr. L. L. 5, § 96 Müll.; cf. Isid. Orig. 12, 2].

  1. I. Cattle for ploughing; and collectively, a herd (but jumentum, contr. for jugimentum from jugum, draught-cattle; cf. Dig. 50, 16, 89); most freq. in the plur.: cornifrontes armentae, Liv. Andron. l. c.; Enn. l. c.: At variae crescunt pecudes, armenta feraeque, Lucr. 5, 228; cf. id. 1, 163: grex armentorum, Varr. R. R. 2, 5, 7: greges armentorum reliquique pecoris, Cic. Phil. 3, 12 fin.; so Vulg. Deut. 28, 4: ut accensis cornibus armenta concitentur, Liv. 22, 17: armenta bucera, Ov. M. 6, 395.
    In the sing.: armentum aegrotat in agris, Hor. Ep. 1, 8, 6: pasci Armentum regale vides, Ov. M. 2, 842; 8, 882; 11, 348: armentum agens, Liv. 1, 7: ad armentum cucurrit, Vulg. Gen. 18, 7; ib. Exod. 29, 1; ib. Ezech. 43, 19 et saep.
  2. II. Transf.
    1. A. Of horses or other large animals: bellum haec armenta minantur, Verg. A. 3, 540.
      In sing.: sortiri armento subolem, Verg. G. 3, 71; Ov. F. 2, 277; Col. 7, 1, 2; Plin. 8, 42, 66, § 165; 11, 49, 110, § 263: hos (cervos) tota armenta sequuntur, Verg. A. 1, 185: armenta immania Neptuni, the monstrous beasts of Neptune, id. G. 4, 395.
    2. B. A herd, drove, as a collective designation; with gen.: armenta boum, Verg. G. 2, 195; so Vulg. Deut. 8, 13; ib. Judith, 2, 8: multa ibi equorum boumque armenta, Plin. Ep. 2, 17: cynocephalorum, id. ib. 7, 2, 2.
    3. C. For a single cow, ox, etc.: centum armenta, Hyg. Fab. 118.