* Noun: This is the most common usage. It refers to the connection between two or more people, things, or ideas.
* Verb: While less common, it can be a verb meaning "to establish a connection." For example, "The two companies decided to relationship."
* Adjective: Though rarer, it can function as an adjective meaning "relating to or connected with a relationship." For example, "They had a relationship problem."
To determine the part of speech, you need to look at how the word is used in the specific sentence.