http://www.thefreedictionary.com/idiom
In the English expression to kick the bucket, a listener knowing only the meanings of kick and bucket would be unable to deduce the expression's true meaning: to die. Although this idiomatic phrase can, in fact, actually refer to kicking a bucket, native speakers of English rarely use it so. Cases like this are "opaque idioms."
Literal translation (word-by-word) of opaque idioms will not convey the same meaning in other languages – an analogous expression in Polish is kopnąć w kalendarz (“to kick the calendar”), with “calendar” detached from its usual meaning, just like “bucket” in the English phrase. In Bulgarian the closest analogous phrase is da ritnesh kambanata ("да ритнеш камбаната", “to kick the bell”); in Dutch, het loodje leggen (“to lay the piece of lead”); in Finnish, heittää lusikka nurkkaan (“to throw the spoon into the corner”); in German, den Löffel abgeben (“to give the spoon away”) or, closer to the English idiom, im [contraction of in dem] Eimer sein ("to be gone into the (waste)bucket"); in Latvian, nolikt karoti (“to put the spoon down”); in Portuguese, bater as botas (“to beat the boots”); in Danish, at stille træskoene ("to take off the clogs"); in Swedish, trilla av pinnen ("to fall off the stick"); and in Greek, τινάζω τα πέταλα ("to shake the horse-shoes"). In Brazil, the expression “to kick the bucket” (chutar o balde) has a completely different meaning (to give up something complicated, as a bucket kicked makes too much noise, demonstrating impatience).
Some idioms, in contrast, are "transparent idioms" [5]: much of their meaning does get through if they are taken (or translated) literally. For example, "lay one's cards on the table" meaning to reveal a secret. Transparency is a matter of degree; "spill the beans" and "leave no stone unturned" are not entirely literally interpretable, but only involve a slight metaphorical broadening.
Another category of idioms is a word having several meanings, sometimes simultaneously, sometimes discerned from the context of its usage. This is seen in the (mostly un-inflected) English language in polysemes, the common use of the same word for an activity, for those engaged in it, for the product used, for the place or time of an activity, and sometimes for a verb.