Lewis & Short

1. aggĕro (adg-), āvi, ātum, 1, v. a. [agger].

  1. I. Lit., to form an agger, or to heap up like an agger; hence, in gen., to heap up, pile up (cf. cumulare; only poet. and in post-Aug. prose): aggerat cadavera, Verg. G. 3, 556: Laurentis praemia pugnae aggerat, id. A. 11, 79: ossa disjecta vel aggerata, Tac. A. 1, 61; 1, 63.
  2. II. Transf.
    1. A. To heap up, i. e. to augment, increase: incenditque animum dictis atque aggerat iras, Verg. A. 4, 197, and 11, 342: omne promissum, Stat. Th. 2, 198.
    2. B. To fill, fill up: spatium, Curt. 4, 2.
    3. C. Aggerare arborem, in gardening, to heap up earth around a tree in order to protect the roots, Col. 11, 2, 46.