What part of speech is cost?

"Cost" can be a few different parts of speech, depending on how it's used:

* Noun: This is the most common usage. It refers to the price or expense of something.

* Example: "The cost of living has increased."

* Verb: This refers to the act of spending money or resources.

* Example: "The new project will cost millions of dollars."

* Adjective: This is less common, but it can be used to describe something as expensive.

* Example: "That's a costly mistake."

So, the part of speech for "cost" depends on its context in a sentence.