Home › Words › R › rockfillrockfillrockfill · noun — A dam's embankment of compacted free-draining granular earth, often containing rocks, with an impervious zone.Definition from Wiktionary (CC BY-SA 3.0).EtymologyFrom rock + fill.nounA dam's embankment of compacted free-draining granular earth, often containing rocks, with an impervious zone.Definitions & examples from Wiktionary (CC BY-SA 3.0).