What part of speech is the word middle?

The word "middle" can be several parts of speech depending on its context:

* Adjective: Describing something located in the center. Example: "The middle child is always the most rebellious."

* Noun: Referring to the center point of something. Example: "They met in the middle of the park."

* Adverb: Describing an action or state as being in the middle. Example: "He stood middle-aged and lost in thought."

Let me know if you'd like a sentence to illustrate a specific usage of "middle"!