Definition of "jettee"

[I]nſtead of demolition, they found conſtruction; for the French vvere then at vvork on the repair of the jettees. On the remonſtrances of General [Henry Seymour] Convvay, ſome parts of theſe jettees were immediately deſtroyed.

1769, [Edmund Burke], Observations on a Late State of the Nation, London: […] J[ames] Dodsley, […], page 86