What part of speech is the word understood?

The word "understood" can be a few different parts of speech depending on its context:

* Verb (past participle): This is the most common usage. For example: "The instructions were understood by everyone."

* Adjective: This is less common but still valid. For example: "She gave me an understood look."

* Interjection: This is very informal and usually used in a conversation to confirm agreement. For example: "You're coming to the party, right? Understood."

To determine the part of speech, you need to look at the context of the sentence.