to build up the level or slope of (a riverbed, valley, etc.) by the deposit of sediment
Origin of aggradeag- (var. of ad-) + grade
transitive verbag·grad·ed, ag·grad·ing, ag·grades
To fill and raise the level of (the bed of a stream) by deposition of sediment.
(third-person singular simple present aggrades, present participle aggrading, simple past and past participle aggraded)
ad- + gradation