An idiom (Latin: idiomī, "special property", from Greek: ἰδίωμα – idíōma, "special feature, special phrasing, a peculiarity", f. Greek: ἴδιος – ídios, "one’s own") is a phrase or a fixed expression that has a figurative, or sometimes literal, meaning. Categorized as formulaic language, an idiom's figurative meaning is different from the literal meaning. There are thousands of idioms, occurring frequently in all languages. It is estimated that there are at least twenty-five thousand idiomatic expressions in the English language.
The following sentences contain idioms. The fixed words constituting the idiom in each case are bolded:
Each of the word combinations in bold has at least two meanings: a literal meaning and a figurative meaning. Such expressions that are typical for a language can appear as words, combinations of words, phrases, entire clauses, and entire sentences.
Expressions such as these have figurative meaning. When one says "The devil is in the details", one is not expressing a belief in demons, but rather one means that things may look good on the surface, but upon scrutiny, undesirable aspects are revealed. Similarly, when one says "The early bird gets the worm", one is not suggesting that there is only one opportunity; rather one means there are plenty of opportunities, but for the sake of the idiom one plays along, and imagines that there is only one. Alternatively, the figurative translation of this phrase is that the most attentive and astute individual, or perhaps the hardest working or most opportunistic receives the most desirable opportunity. On the other hand, "Waste not, want not" is completely devoid of a figurative meaning. It counts as an idiom, however, because it has a literal meaning and people keep saying it.
Many idiomatic expressions, in their original use, were not figurative but had literal meaning.
For instance: spill the beans, meaning to reveal a secret, originates from an ancient method of democratic voting, wherein a voter would put a bean into one of several cups to indicate which candidate he wanted to cast his vote for. If the jars were spilled before the counting of votes was complete, anyone would be able to see which jar had more beans, and therefore which candidate was the winner. Over time, the practice was discontinued and the idiom became figurative.