Under what condition can a written instrument be considered forgery?

A written instrument can be considered forgery when it has a forged signature because forgery fundamentally involves the unauthorized signing of a document in order to deceive another party. This includes imitating someone else's signature with the intent to use the document for fraudulent purposes.

In the context of forgery laws, the act of forging a signature directly challenges the authenticity of the written instrument, making it legally reproduce an original document that has not been properly authorized by the person whose signature it mimics. This is a critical aspect of defining forgery because the deceit against an individual or entity is centered on the misrepresentation of the signature.

The other conditions mentioned don't fully encapsulate the essence of forgery. For instance, if an instrument is entirely printed or not signed at all, it may still not involve the fraudulent intent that characterizes forgery. Similarly, a document that is written without consent might involve other legal issues but does not necessarily imply that a forgery has occurred unless it specifically includes a false signature.