Writers Talk About Writing
Finding Fossilized Words in Phrases Frozen in Time
The correct answers are pique and bate, but if you chose peak or bait, don't feel bad. Sure, some of us may know pique from the phrase "a fit of pique," where it means "annoyance at not being treated properly," but "pique my interest" is increasingly rendered nowadays as "peak my interest" because pique is a word most people don't know.
All of us have a tendency to replace fossilized words whose nuances have been lost with a more standard definition of that word, or a different word entirely. Through this process, phrases, like words, can change meaning over time. Thus, the bated in "bated breath" (which is a shortened version of abate, meaning "to lessen") starts out mistakenly being analyzed as the more common word with that sound, "baited breath," even if the known definitions of baited don't particularly relate to breath.
Helping this phrasal change along is the fact that these frozen phrases are often heard and not read, or read in an unfamiliar context, which can lead to confusion about what they mean, particularly when they contain words only encountered in in this one way. One of the definitions of exact, now all but obsolete, is "to demand and obtain something." This is the meaning that exact has in the phrase "exact revenge," but since this meaning of the verb has little life independent of this phrase, one can see the phrase rendered as "extract" or even "enact revenge."
Once upon a time, when you were giving someone control, not being too strict, you were said to be giving them "free rein," as if you were letting the reins that control a horse go slack. The farther we get from horses and buggies, the more obscure this analogy becomes. It is not unusual these days to see this expression spelled "free reign," as though the person in question is the monarch of their own little kingdom. Although this could be viewed as just a spelling mistake that is becoming increasingly familiar, it actually changes the phrase, becoming what some linguists call an eggcorn. Having "free rein" suggests a dependable horse. "Free reign" suggests a more despotic situation.
In some cases, an obscure word remains in place in a phrase, but its definition changes. The phrase "begging the question" is still used, but it most often now refers to when a situation forces a question to be addressed: The question is begging to be asked. But when this phrase originated as a mistranslation of a Greek expression, "to beg the question" meant to engage in circular reasoning, assuming the answer to the question before answering it honestly — in other words to make a beggar of the question, to render the point moot. This sense of the phrase employs a figurative use of the verb form of beggar, which originally came into English in the 1400s, but has since largely fallen out of use.
(Moot is actually another interesting case of meaning shift. As used above, moot the adjective means "not worth considering," and it is used when something is rendered inconsequential by circumstances. The verb form of moot, however, means "to debate, talk, discuss," and there isn't the sense of a "lack of importance" as in the adjectival case.)
The prodigal in the biblical parable of the prodigal son (Luke 15:11 – 32) refers to a son's wasteful spending of the inheritance he obtained from his father. This meaning of prodigal as "wasteful" is preserved in the related word prodigious, which can mean anything above and beyond normal limits. Prodigal, however — and often the phrase "prodigal son" — have come to refer to the end of the tale, when the son returns to his family, with prodigal being widely accepted as "one who returns after a long time away." What's interesting about prodigal's current meaning is that it fills a gap in English — before prodigal, there wasn't a really a word in popular use. Phrases like "black sheep of the family" or "formerly estranged" don't really capture the situation, and certainly not as concisely.
So at best, phrasal change can enrich our language. And at worst, it gives us the ability to recreate from fossilized evidence the story of how our language (and culture) has changed over time. Fascinating, unless of course our interest in that kind of thing has already peaked.