As we all know, any statement in English, whether literal or idiomatic, consists of a combination of any or all of the following words:
content words (nouns, pronouns, verbs, adjectives, and adverbs),
function words (prepositions, conjunctions, conjunctive adverbs), and
articles (“a,” “an,” “the,” etc.). The content words are, of course, the carriers of meaning of the language; the function words are the connectives of ideas and logical operators of the language; and the articles are limiters to indicate the definiteness of nouns. And, in relation to your questions, I would say this early that the most semantically important of these types of words are the content words.
Now, you ask me if a change in a single word of an idiomatic expression would alter an idiomatic expression. I would say that it would depend on what kind of word is changed. I don’t think the idiom would change if a preposition like, say, “on” in the idiomatic expression “on the same wavelength” is mistakenly substituted with “in” (“
in the same wavelength") or changed in a regional dialect of English to “at” (“
at the same wavelength). The intended meaning of the idiom will still come through, but the change in the preposition will definitely become the butt of long discussions about its grammatical correctness—precisely like what we are doing right now. I might add that the same thing would happen if someone cluelessly changes the article “the” in the expression “in the same wavelength” to “a” so that the expression becomes “in
a same wavelength.” We can conclude that the person who did that is grammatically dull, but I think it will be dishonest to say that the intended idiomatic meaning of the expression “on the same wavelength” is changed or lost in the process.
On the other hand, maxsims, there's no doubt that the idiomatic expression will profoundly change in meaning if any of its content words is changed. If, for instance, we change the adjective “same” in “on the same wavelength” to “identical,” I think we’d be treading on treacherous semantic grounds indeed. The expression would now read as “on the
identical wavelength.” In this case, I would say that the meaning of the idiomatic expression has been lost, such that the expression now has a purely literal sense.
An even more serious alteration of meaning would take place, of course, if we change the content word “wavelength” to, say, “frequency” or “amplitude.” This time we’ll have an altogether different expression. To say “on a different
frequency” or “on a different
amplitude” may still faintly echo some of the denotations of “on a different wavelength,” but it is indisputable that none of them means the same thing as the original “on the same
wavelength.”
Now, having answered your first question in every conceivable particular, I would like to quote from a column I wrote about idioms subsequent to the publication of
Give Your English the Winning Edge.
You can read the complete essay by clicking this link (I posted it in the Forum as early as last September 5, 2009), but in answer your third question, I am quoting this particular passage:
Indeed, the true idioms of a language share three common features that differentiate them from plain and simple collocations: (1) They are not compositional, (2) Their words are not substitutable, and (3) They are not modifiable.
An idiom is not compositional. We can’t compose or construct an idiom from the individual meanings of its component words. For instance, the idiom “take a lot of flak” (get strongly opposed or heavily criticized) draws its metaphorical power from the quandary of combat pilots whose aircraft are met by bursting shells (the “flak”) fired from anti-aircraft guns. In its current form, however, this collocation no longer has anything to do with combat pilots, flak, or aerial warfare; only the aspect of strong opposition is retained in its meaning and it has since been largely applied to serious intra-office or political disputes.
The words of an idiom are not substitutable. When a word in a true idiom is replaced with a related word or even a close synonym, the idiom collapses and loses its intended meaning. This is what happens to “take a lot of flak” when we change “take” to “sustain” and “flak” to “gunfire” to form “sustain a lot of gunfire”—a different but purely literal collocation.
An idiom is not modifiable. Changing the way the words of an idiom are put together or inflected alters its meaning or, worse, changes it beyond recognition. Imagine the semantic consequences when we modify “take a lot of flak” to, say, “get flakked a lot” or “take so much flakking”!
True idioms are meant to make ourselves quickly understood through the common knowledge and understanding we share with our audience, so it doesn’t really pay to monkey around with them.
This has been a long explanation, maxsims, but I do hope that I have clarified things and have answered your questions to your full satisfaction.
