What is a participle that ends in ing and functions as noun.?

A participle that ends in "-ing" and functions as a noun is called a gerund.

Here are some examples:

* Swimming is my favorite way to exercise.

* Reading can be a very relaxing activity.

* Cooking is a skill that takes time to develop.

Key features of gerunds:

* They are formed by adding "-ing" to the base form of a verb.

* They function as nouns in a sentence, meaning they can be the subject, object, or complement of a verb.

* They often have an object or an adverb modifying them.

Let me know if you have any other questions!