[L. agger, f. agger-ĕre (see AGGEST).] A mound; esp. the earthen mound or rampart of a camp, formed by the earth excavated from the ditch; a technical term of Roman Antiquities, extended to similar ancient works.
1398. Trevisa, Barth. De P. R., XIX. cxxix. (1495), 938. Agger is an hepe of stones other a token in the hyghe waye.
1724. De Foe, etc., Tour Gt. Brit. (1769), III. 114. Before the Gate is an Agger, said to be the Burying-place of Hengist.
1877. Ll. Jewitt, Half-hrs. among Eng. Antiq., 16. A circle of somewhat irregular form … surrounded by an agger and ditch.
