“Redoubtable” is a bit of an odd word. It looks like it ought to mean somebody or something you doubted before and now you realize you should doubt again. For example, you might expect to use it this way: “in spite of my worry about whether that bridge was safe, I made it across. But I find it redoubtable now that it’s started shaking that way.”
If you did use it that way, of course, you’d be pretty far off the mark. “Redoubtable” actually means formidable; something or someone “worthy of respect because of strength, endurance, or ability,” according to the dictionary. The Brantford Expositor used the word correctly in 2006: “She was gutsy, brave, talented, and skilled beyond measure in the art of self-promotion. She was, in a word, redoubtable.” I don’t know who they were talking about; maybe one of the Kardashians?
So the situation we’re left with is a word that means kind of the opposite (in a way) of what it looks at first glance like it ought to mean. There’s usually a story behind that kind of thing, and sure enough, there’s one about “redoubtable.” The word “doubt” came from the Latin word “dubitare” (to waver). A related Latin word was “dubius” (uncertain), which is the source of the English word “dubious” and maybe also “duo,” because if you’re “dubious” you might be wavering between two choices.
“Doubt” entered English in the 1200s (so technically what it entered was Middle English). It arrived from Latin by way of Old French, which had the word “dubitare” (doubter). At first the English word was spelled more sensibly as “doute,” since the “b” just sits there and doesn’t do anything. But in the 1400s people in England realized afresh that the word came from “dubitare,” and they put the “b” in to make it seem more connected to its roots. Interestingly, the “b” in the French word went in and out of style a couple of times too between the 13th and 17th centuries. People seemed to have doubts about the right way to spell it.
Although the original Latin root “dubitare” meant almost exactly what we mean by “doubt” today, an additional meaning arose in France for the word. While it retained its original meaning, in Old French it also meant “to be afraid of something.” That became the first meaning of the English word when it initially entered use. You can see that sense of “doubt” in this quote from Samuel Pepys in 1665: “Doubting that all will break in pieces in the Kingdom…”
And here’s where we come to “redoubt” — that word was also borrowed from Old French, and the “re” acts as an intensifier. In this case what “re” is intensifying is that older meaning of “doubt” that’s related to fear. If you fear something you might also be said to respect it, and although the meaning of “doubt” itself has shifted away from fear and more toward uncertainty, “redoubt” never shared in that shift. Redoubt has always had to do with respect), and the noun form of “redoubt” means a fortress or refuge. In modern usage “redoubt” is more often used figuratively (possibly because we don’t use fortresses so much any more). So you’ll tend to see something like this most of the time: “The last redoubt of the true Bohemians, a rookery in Polk street, has been torn down to make room for the ornate New Babylonia.” I mean, you probably won’t see that particular line, because it was written in 1925. But if you’re reading this, you’re redoubtable enough that I have no doubts you’ll find your own examples.
