- Fortification.
- an isolated work forming a complete enclosure of any form, used to defend a prominent point.
- an independent earthwork built within a permanent fortification to reinforce it.
- any safe and secure place or situation; refuge; stronghold: Lebanon has represented one of the last redoubts of Christianity in the Middle East.
- an active volcano in S Alaska, on the Alaska Peninsula: highest peak in the Aleutian Range. 10,197 feet (3,108 meters).
- an outwork or detached fieldwork defending a pass, hilltop, etc
- a temporary defence work built inside a fortification as a last defensive position
