- underrun⇄noun 1. undercurrent.
2. the act or fact of underrunning.
3. an amount by which something is underrun. - underrun⇄underrun, verb, -ran,-run,-running,noun.
- underrun⇄v.t. 1. to pass or move beneath.
2. to move along in a boat beneath (as a cable or net) to make an inspection or repair.
3. to run below capacity.
Ex. to underrun a power plant.