Definition of overballast in US English:

overballast

verb

  • with object To overload (a ship) with ballast; to provide (a vehicle, etc.) with excessive weight of ballast.

Origin

Early 17th century; earliest use found in William Cornwallis (c1579–1614), essayist. From over- + ballast.

Pronunciation

overballast

/ˌəʊvəˈbaləst/