* Noun: This is the most common usage. It refers to the act of contributing something, or the thing that is contributed.
* Example: "Their generous contributions helped build the new library."
* Verb: Less common, but "contribute" can be used as a verb meaning "to give something for a common purpose."
* Example: "Please contribute your ideas to the discussion."
* Adjective: This is even less common, but it's possible to use "contributory" to mean "helping to cause something."
* Example: "The storm's heavy rain was a contributory factor in the flooding."
Let me know if you have a specific sentence in mind and I can tell you for sure what part of speech "contributions" is in that sentence.