* Language is constantly evolving: New words are created, old words take on new meanings, and languages change over time.
* No definitive list: There is no single, universally accepted dictionary or list of all common nouns.
* Subjectivity: What is considered a "common noun" can be subjective. Some words might be common in one language or region but not in others.
However, we can say that there are likely tens of thousands, if not hundreds of thousands of common nouns in the world.
Think about all the categories of things that common nouns represent:
* Physical objects: cars, trees, books, phones, etc.
* Concepts: love, freedom, justice, happiness, etc.
* Places: countries, cities, mountains, rivers, etc.
* People: doctor, teacher, artist, scientist, etc.
* Animals: dog, cat, bird, fish, etc.
* Activities: running, swimming, reading, singing, etc.
And within each of these categories, there are countless specific nouns.