Barbican

noun

1. A tower or other fortification on the approach to a castle or town, especially one at a gate or drawbridge.
2. In medieval fortification, an outwork of a castle or fortified place.
3. A loophole.
4. A channel or scupper in a parapet for the discharge of water.
5. A scansorial barbet of the family Capitonidæ and subfamily Pogonorhynchinæ, or the genus Pogonias in a broad sense. The barbicans are all African, like the barbions.