[currere]

Curious that you have a negative view of that. When I come across a word I don't know I am usually too lazy to look it up, and so I infer its meaning. But I don't know if I infer it correctly! I'm convinced this is how we end up with word meaning mutations; the traces of which, of course, are the object of etymology.

Coordinating a mapping from reality to our internal world of ideas is hard enough without basic disagreements on the meanings of words. I find it hard to take joy, as some descriptivists do, in words that also mean their opposite!

I like the idea of writing a word and its page number inside the back cover of a book for looking up later but I never seem to have a pen to hand either.

[thaumasiotes]

> so I infer its meaning. But I don't know if I infer it correctly! I'm convinced this is how we end up with word meaning mutations

Sometimes. Sometimes something more intricate happens.

是 is, in modern Chinese, the verb "to be". Like other Mandarin verbs, it works in pretty much the way an English speaker would expect, coming after the subject of the sentence and before the object: "I am an American": 我 [I] 是 [am] 美国人 [an American].

That's also how verbs work in Old Chinese. It isn't how predication works, though; where modern Mandarin has (thing)是(other thing), Old Chinese says (thing)(other thing)也. "Lao Tzu was a man of Ch'u": 老子 [Lao Tzu] 楚国人 [a man of Ch'u] 也 ["was"]. 是 is an important word in Old Chinese, but it's not even a verb - it's the proximal demonstrative pronoun, "this".

How does that turn into the verb "to be"? Well, "this" is often used to refer back to a complicated noun phrase. So you see a reanalysis:

鱼出遊从容是鱼乐也

鱼 [fish] 出遊 [come out on a pleasure trip] 从容 [(and) relax]。是 [this] 鱼乐 [fish happiness] 也 ["is"]。

鱼 [fish] 出遊 [com(ing) out on a pleasure trip] 从容 [(and) relax(ing)] 是 [is] 鱼乐 [fish happiness]。

The meaning of the utterance didn't change at all (though we forgot that it was supposed to end with 也). But the meaning of 是 inside it changed quite a bit.

[thaumasiotes]

Another way for semantic shift to occur:

- You have a word, and it has a meaning. The nature of this kind of thing is that this word will be used more often in some contexts than in other contexts.

- Someone who knows the meaning perfectly well extends it a bit in a straightforward way. For example, "illuminate" primarily means to shine light on something, making that thing easier to see. But it can be used in an extended sense to refer to making a "murky" concept easier to understand. Anyone who knows the primary meaning will understand why the secondary meaning makes sense.

- So now we have one context where the word is likely to mean one thing, and another context where the same word is likely to mean something a little bit different.

- But the world changes. The old context may become less common. As that happens, what was a metaphorically extended meaning may turn into the ordinary primary meaning.

- All of this happened without anyone learning the wrong meaning of the word. It was always being used correctly. But the meaning shifted anyway.

[currere]

Thank you, I enjoyed your illuminating comments, and for the search phrase "semantic shift". I should have been more cognizant of metaphorical extension, having recently read [0] which claims "tall" went from "swift" to "vertically large" via "skillful" ("tall of hand") then "exaggerated" ("tall story").

[0] http://theconversation.com/five-words-that-dont-mean-what-yo...