Is the word signed a subject or predicate?

The word "signed" can be either a subject or a predicate, depending on the sentence structure.

Here are examples:

Subject:

* Signed the document. (Here, "signed" acts as the subject performing the action of signing.)

Predicate:

* The document was signed. (Here, "signed" is part of the predicate, describing the state of the document.)

Let me know if you can provide the full sentence you're looking at!