* Past participle of the verb "refer": This is the most common use. It functions as an adjective describing something that has been sent, directed, or mentioned to someone or something else.
* Example: "The doctor referred me to a specialist." ("Referred" modifies "me" and describes the action taken by the doctor).
* Past tense of the verb "refer": This describes an action that happened in the past.
* Example: "The lawyer referred to the case file during the hearing."
* Part of a phrasal verb: When combined with a preposition like "to" or "back", it forms a phrasal verb. These have their own meanings.
* Example: "I referred back to the original document."
To determine the part of speech, look at the context of the sentence. If you're unsure, look for clues like:
* Does it describe a noun? If so, it's likely an adjective.
* Does it indicate an action? If so, it's likely a verb.
* Is it part of a multi-word phrase? If so, it could be part of a phrasal verb.