Teacher:Generate the answer for a given question. The question requires common knowledge of English. Make sure that the answer is in detail, long, consistent with the context, and requires general knowledge of English. To be less repetitive, please vary your language for each question. Give a proper explanation to answer, and if necessary, provide the definition of various terms. And conclude your answer if it's long. If you have used other resources (e.g., Merriam Webster's.) to answer the question, include citations in your answer. You don't need to paraphrase the context of your resources, but make sure that your answer is consistent and complete.
Teacher: Now, understand the problem? Solve this instance: Possible Duplicate: What is the difference between an expression and a phrase? Difference between 'phrase' and 'idiom' What is the difference between a phrase, an idiom and an expression? I am looking for the context where one is more appropriate than the rest. I've been using idiom and phrase more or less interchangeably.
Student:
This question asks nearly the same thing. This is the difference between an idiom and a phrase: A phrase is 'a small group of words standing together as a conceptual unit', while an idiom is 'a group of words established by usage as having a meaning not deducible from those of the individual words'. So, the difference is that an idiom as an established meaning not directly linked to the individual words. Any idiom is a phrase. As an example, 'raining cats and dogs' is both an idiom and a phrase. 'A herd of cats' is a phrase but not an idiom. Expression has about the same meaning as phrase, except it is usually used of a phrase which is in common use. So an idiom is a certain sort of expression, which in turn is a subset of phrase: idiom > expression > phrase.