1911 Encyclopædia Britannica/Redoubt

REDOUBT (Fr. redoute, from Med. Lat. reductus, a place of retreat, refuge, reducere, lead back, retire; the intrusive b is due to the O. Fr. redoubter, to fear, Lat. dubitare, to doubt), a term in fortification for a small closed work of plain trace, generally used in conjunction with lines of infantry trenches (see Fortification and Siegecraft). The term “reduit” (Fr. réduit), often confused with “redoubt,” is only used for a keep or interior refuge for the garrison of a larger work, corresponding, on a small scale, to the citadel of a fortress.