Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
ăd-aggĕro, āvi, ātum, 1, v. a. (a double ad, as in adalligo), to heap up: cum ver adpetet, terram adaggerato bene, Cato, R. R. 94: so, terram circa arborem, Col. 5, 11, 8: terra Nilo adaggerata, brought down or deposited by the Nile, Plin. 13, 11, 21, § 69: nitro et sale adaggeratis, id. 36, 12, 17, § 81.