rə̇ˈdan noun
( -s )
Etymology: French, alteration of redent, from re- + dent tooth, from Latin dent-, dens — more at tooth
: a fortification having two parapets forming a salient angle, an unfortified entrance usually protected by its location (as on the bank of a stream, at the head of a bridge, or in advance of a strong line), and often a connection (as by curtains) with other such fortifications as a simple form of fieldwork