an idea worth some thought

[ROFTOK]

I have looked up in dictionaries the word WORTH and I found that they classify WORTH used in similar sentences with different parts of speech:

an idea worth some thought

Some dictionaries say it's a preposition others say it's an adjective. How come?

 

[emsr2d2]

an idea worth some thought

I have looked up in dictionaries the word WORTH in some dictionaries and I found that they classify WORTH it (used in similar sentences) with as different parts of speech. Some dictionaries say it's a preposition; others say it's an adjective. How come?

In that sentence, it's a preposition. You can find more information HERE.

In future, please provide links to the relevant dictionary entries with the definition and the example sentences they give.

 

[ROFTOK]

If it's a preposition, how come this dictionary says that it's an adjective?

https://www.collinsdictionary.com/dictionary/english/worth

ADJECTIVE (governing a noun with prepositional force)
1.
worthy of; meriting or justifying
it's not worth discussing
an idea worth some thought

 

[5jj]

Some dictionaries say it's a preposition others say it's an adjective. How come?

The simple answer is that some grammarians/lexicographers have different ideas when it comes to parts of speech.