* Verb: This is the most common usage. It describes an action of coming to a mutual understanding.
* Example: "We agreed to meet at the park."
* Adjective: This indicates a state of being in agreement.
* Example: "The decision was agreed upon by all parties."
* Past participle: This form can act as part of a verb phrase, or an adjective.
* Example: "We have agreed to meet at the park." (Verb phrase)
* Example: "The agreed upon price was $100." (Adjective)
The best way to determine the part of speech is to look at its role in the sentence and the context in which it is used.