redoubt

Based on its spelling, you might think that "redoubt" shares its origin with words such as "doubt" and "redoubtable," both of which derive from a Latin verb, dubitare. But that's not the case. "Redoubt" actually derives via French and Italian from a different Latin verb - reducere, meaning "to lead back," the same root that gives us "reduce." How that "b" ended up in "redoubt" is a lingering question, but some etymologists have posited that the word might have been conflated with another "redoubt" - a now-archaic transitive verb meaning "to regard with awe, dismay, or dread." Unlike its homographic twin, that "redoubt" does derive from the same root as "doubt" and "redoubtable."