Fixed phrases comes from ancient classics or works, historical stories and people's oral stories. It is a unique and long-used fixed phrases in ancient Chinese vocabulary.
The meaning of idioms is incisive, often implied in literal meaning, rather than simply adding up the meanings of their components.
Its structure is tight, and it is generally impossible to change the word order, extract or increase or decrease its components at will.
Its form is mostly four characters, and there are also some three characters and multi-characters, which are mostly composed of four characters. Simply put, idioms are words that are well known, can be quoted from classics, have clear sources and allusions, and are highly used.
Extended data
Idioms are holistic in meaning. Its meaning is often not the simple addition of its constituent meanings, but the overall meaning further summarized on the basis of its constituent meanings.
For example, "Smith", on the surface, means "the fox uses the tiger's strength", but in fact, it is "bullying people with the strength of others"; "Cooked by a dead rabbit and a dead dog" superficially means "Cooked by a dead rabbit and a dead hunting dog", but actually means "Those who serve the rulers are abandoned or killed when they are finished".
Idioms are different from two-part allegorical sayings: two-part allegorical sayings are a fixed sentence, which must be composed of two parts: the first part is a metaphor for things, and the second part is a positive explanation. In order to get vivid, vivid and concrete expression effect, we can also quote two-part allegorical sayings like idioms.
Reference materials? Baidu encyclopedia-idioms