* Constantly Evolving: Idioms are informal expressions that change with time and culture. New idioms emerge, and old ones fall out of use.
* Regional Differences: Idioms vary greatly depending on the region and dialect. An expression might be common in one part of the world and completely unknown elsewhere.
* Difficult to Define: The very definition of an idiom is subjective. Some expressions are clearly idioms, while others are more debatable.
Estimates:
* Oxford English Dictionary: Estimates around 25,000 idioms in common usage.
* Other Sources: Some sources suggest the number could be even higher, potentially reaching into the tens of thousands.
Key takeaway: It's safe to say there are a vast number of idioms in the English language, with no single, definitive count available.