One of the major obstacles to machine translation, the usefulness of phrasebooks, and learning languages in general. Poor understanding of this concept is common in people who have never learned a foreign language to at least semi-fluency, causes them to misapply words and leads to a false sense of security.

Basically, the problem is this: words in natural languages often cover more than one abstract concept, or cover only some aspects of a complex concept. Unfortunately, these boundaries are usually completely arbitrary, as there is no single logical mapping between words and concepts. Therefore, languages frequently differ in how they map words to meanings.

An example: the German adjective "scharf" covers several concepts:

  1. sharp (as in "this knife is sharp")
  2. hot/spicy (as in "Be careful, the curry sauce is hot")
  3. sexually attractive (as in "Look, what a babe!")
Now, while there exists an English word (hot) that covers meanings 2 and 3, it definitely doesn't cover meaning 1. However, "hot" has another meaning (in respect to temperature) that the German word does not cover - temperature-hot in German is "heiß" (which can also mean sexually-hot, but not spicy-hot).

This effect plays hell on machine translation, because the correct translation must be derived from context, but the context isn't really available yet - you are still in the stage of parsing individual words, and other words in the vicinity may also have meaning ambiguities.

A similar effect occurs with idioms and standard phrases, such as sumimasen or itte kimasu in Japanese, which have complex meanings that do not directly correspond to any English phrase, but phrasebooks often only give the most common meanings, since saying that "sumimasen" means both "I'm sorry / Excuse me" and "Thank you" would beg an explanation beyond the scope of a phrasebook. The result is that the phrases are often misapplied or misunderstood.

To summarize: words and phrases in languages other than your own will often not have a single, direct translation to your native tongue; correct usage can often be learned only from observing native speakers a lot. Don't let this phenomenon surprise you - expect it.

By the way, loanwords are not, as getzburg suggests in his wu, excluded from this rule. "Anime" is in fact a good example, as it is used for all animation, including Disney, in Japan, while to western anime fans, anime and Disney are practically antipodes. In German, the English word handy is used to mean "celphone". In Japanese, the English word cunning means "cheating in a test", and the German word arbeit is used specifically for part-time jobs (as opposed to real employment) while in German, it mens "work" in general.