Lewis & Short

agger, ĕris, m. [ad-gero].

  1. I. Things brought to a place in order to form an elevation above a surface or plain, as rubbish, stone, earth, sand, brushwood, materials for a rampart, etc. (in the histt., esp. Cæs., freq.; sometimes in the poets): ab opere revocandi milites, qui paulo longius aggeris petendi causā processerant, Caes. B. G. 2, 20: aggere paludem explere, id. ib. 7, 58; cf. id. ib. 7, 86: longius erat agger petendus, id. B. C. 1, 42; 2, 15 al.: superjecto aggere terreno, Suet. Calig. 19; cf. id. ib. 37: implere cavernas aggere, Curt. 8, 10, 27: fossas aggere complent, Verg. A. 9, 567: avis e medio aggere exit, from the midst of the pile of wood, Ov. M. 12, 524.
    But far oftener,
  2. II. Esp.
    1. A. The pile formed by masses of rubbish, stone, earth, brushwood, etc., collected together; acc. to its destination, a dam, dike, mole, pier; a hillock, mound, wall, bulwark, rampart, etc.; esp. freq. in the histt. of artificial elevations for military purposes: tertium militare sepimentum est fossa et terreus agger, a clay or mud wall, Varr. R. R. 1, 14, 2: aggeribus niveis (with snow-drifts) informis Terra, Verg. G. 3, 354: atque ipsis proelia miscent Aggeribus murorum, pleon. for muris, id. A. 10, 24; cf. id. ib. 10, 144: ut cocto tolleret aggere opus, of the walls of Babylon, Prop. 4, 10, 22.
      A dike of earth for the protection of a harbor (Ital. molo), Vitr. 5, 12, 122; Ov. M. 14, 445; 15, 690.
      A causeway through a swamp: aggeres umido paludum et fallacibus campis imponere, Tac. A. 1, 61.
      A heap or pile of arms: agger armorum, Tac. H. 2, 70.
      Poet., for mountains: aggeres Alpini, Verg. A. 6, 830; so, Thessalici aggeres, i. e. Pelion, Ossa, Olympus, Sen. Herc. Oet. 168.
      A funeral pile of wood, Ov. M. 9, 234, and Sen. Herc. Fur. 1216.
      A heap of ashes: ab alto aggere, Luc. 5, 524 Weber.
      A high wave of the sea: ab alto Aggere dejecit pelagi, Luc. 5, 674: consurgit ingens pontus in vastum aggerem, Sen. Hippol. 1015 (cf.: mons aquae, Verg. A. 1, 105).
    2. B. In milit. lang.
      1. 1. A mound erected before the walls of a besieged city, for the purpose of sustaining the battering engines, and which was gradually advanced to the town; cf. Smith’s Dict. Antiq., and Herz. ad Caes. B. G. 2, 12: aggere, vineis, turribus oppidum oppugnare, Cic. Fam. 15, 4; id. Att. 5, 20: esset agger oppugnandae Italiae Graecia, id. Phil. 10, 9: celeriter vineis ad oppidum actis, aggere jacto turribusque constitutis, etc., Caes. B. G. 2, 12: jacere, to throw up, Sall. J. 37, 4; so Vulg. Isa. 29, 3: aggerem exstruere, Caes. B. G. 2, 30: instruere, id. ib. 8, 41: promovere ad urbem, to bring near to the city, Liv. 5, 7.
        Hence, poet.: stellatis axibus agger Erigitur, geminasque aequantis moenia turres Accipit, a mound is built provided with wheels (for moving it forwards), Luc. 3, 455; imitated by Sil. 13, 109.
        Since such aggeres consisted principally of wood, they could be easily set on fire, Caes. B. C. 2, 14: horae momento simul aggerem ac vineas incendium hausit, Liv 5, 7.
        Trop.: Graecia esset vel receptaculum pulso Antonio, vel agger oppugnandae Italiae, rampart, mound, Cic. Phil. 10, 4: Agger Tarquini, the mound raised by Tarquinius Superbus for the defence of the eastern part of the city of Rome, in the neighborhood of the present Porta S. Lorenzo, Plin. 3, 5, 9, § 67; cf. id. 36, 15, 24, n. 2, * Hor. S. 1, 8, 15; Juv. 5, 153; so id. 8, 43; Quint. 12, 10, 74.
        Suet. uses agger for the Tarpeian rock: quoad praecipitaretur ex aggere, Calig. 27.
      2. 2. The mound raised for the protection of a camp before the trench (fossa), and from earth dug from it, which was secured by a stockade (vallum), consisting of sharpened stakes (valli); cf. Hab. Syn. 68, and Smith’s Dict. Antiq.: in litore sedes, Castrorum in morem pinnis atque aggere cingit, Verg. A. 7, 159; Plin. 15, 14, 14, § 47.
      3. 3. The tribunal, in a camp, formed of turf, from which the general addressed his soldiers: stetit aggere saltus Cespitis, intrepidus vultum meruitque timeri, Luc. 5, 317: vix turre senex, cum ductor ab aggere coepit, Stat. Th. 7, 374; cf. Tac. A. 1, 18 Lips.
      4. 4. A military or public road, commonly graded by embankments of earth (in the class. per. only in Verg. and Tac., and always in connection with viae, agger alone belonging only to later Lat.): viae deprensus in aggere serpens, Verg. A. 5, 273: Aurelius agger, i. e. via Aurelia, Rutil. Itiner. 39: aggerem viae tres praetoriae cohortes obtinuere, Tac. H. 2, 24 and 42; 3, 21 and 23.