In linguistics, idioms are usually presumed to be figures of speech contradicting the principle of compositionality. This principle states that the meaning of a whole should be constructed from the meanings of the parts that make up the whole. In other words, one should be in a position to understand the whole if one understands the meanings of each of the parts that make up the whole.
In phraseology, idioms are defined as a sub-type of phraseme, the meaning of which is not the regular sum of the meanings of its component parts. John Saeed defines an idiom as collocated words that became affixed to each other until metamorphosing into a fossilised term. This collocation of words redefines each component word in the word-group and becomes an idiomatic expression. Idioms usually do not translate well; in some cases, when an idiom is translated directly word-for-word into another language, either its meaning is changed or it is meaningless.
When two or three words are often used together in a particular sequence, the words are said to be irreversible binomials, or Siamese twins. Usage will prevent the words from being displaced or rearranged.
The use of idioms and proverbs in a language adds colour to it and makes it more interesting for the listeners.
1. Acid Test
Meaning - Acid test proves the effectiveness of something.
Example - I practiced hard at the dance sessions but the acid test will come when the master will assess our solo performances.
2. Cut the ground from under feet