Bar"bi*can (?), Bar"ba*can (?), n. [OE. barbican, barbecan, F. barbacane, LL. barbacana, barbicana, of uncertain origin: cf. Ar. barbakh aqueduct, sewer. F. barbacane also means, an opening to let out water, loophole.]
( Fort.) A tower or advanced work defending the entrance to a castle or city, as at a gate or bridge. It was often large and strong, having a ditch and drawbridge of its own.
An opening in the wall of a fortress, through which missiles were discharged upon an enemy.
© Webster 1913.