Slip of the meaning of expressions

Question

Numerous expressions get their (popular) meaning largely or totally changed with time. Sometime it is in one language and not the others. Sometimes changes go different ways (cf. formidable or terrific in French vs English). For the ones below, is the change typically French, or is it the same in all languages ?

• décimer (decimate): was killing one over ten, now more like "almost all"
• littéralement (literally) : was meaning to be taken at the face value of the expression, now more like "badly" or "a lot", but not "literally" at all (argh !)

Answer 1

I can’t speak for all languages (or even for all English speakers/English dictionaries), but according to ‘The American Heritage Dictionary’ it seems that the expansion/extension of the meaning of “decimate” that you mention has occurred/is recognized in American English:

For “decimate, in 2005:

”81 percent of the [American Heritage Dictionary] Usage Panel accepted this extension [from its historical, 1/10th meaning to “the killing of any large proportion of a population”] in the [following] sentence: ‘The Jewish population of Germany was decimated by the war,’ even though it is common knowledge that the number of Jews killed was much greater than a tenth of the original population.”

Only 36% of this same panel, however, accepted the word’s further extension to non-human killing/destruction in the following sentence: “The supply of fresh produce was decimated by the nuclear accident at Chernobyl.”

On the other hand, (with the same disclaimer and from the same source), the expansion/extension of “literally” from its traditional, “word-for-word” meaning to its expanded, “really/actually” (cf: your “badly”/“a lot”) meaning and use as an intensifier has met with more resistance (than has “decimate”) in English, especially when used in an attempt to intensify metaphors:

For literally, in 2004 “only 23 percent of the Panel accepted the following sentence, in which “literally” undercuts the sentence's central metaphor: “The situation was especially grim in England where industrialism was literally swallowing the country's youth.”

When used with “a dead metaphor, which functions as a set phrase and evokes no image for most people, … [t]he Panel mustered more enthusiasm … [with] … 37 percent accept[ing]: “He was literally out of his mind with worry.”

”[However,] when there is no metaphor at all, a substantial majority of the Panel was willing to allow ‘literally’ to be used as an intensifier; 66 percent accepted the sentence “They had literally no help from the government on the project.”

(all from ‘The American Heritage Dictionary’ and the “Usage Problems”/“Usage Notes” under their entries for “decimate” and “literally”)

Answer 2

Words (and grammatical structures) change their meaning radically over time in all languages. Or at least, that is the assumption in comparative and historical linguistics and every bit of evidence we have about languages seems to point in that direction.

It is possible to imagine a completely isolated community where the environment would be constant and the change would be minimal but such communities are hard to come by. Even relatively isolated communities like Martha's Vineyard showed linguistic change.

Some change happens in all languages all of the time. But how much change and how it varies depending on external contexts is unknown.