A synpath is something (usually a character) that someone identifies with but not as. Synpath is a tidy name for something you identify with on several levels, which could be a concept that resonates really strongly with you, an animal or mythological creature you feel you act like, or a person or character you share a lot of common behaviors with, among other things. The term synpath is typically seen as being related to the otherkin community, but describes a separate concept. While someone who is otherkin identifies as their kintype, someone with a synpath finds their synpath to be very relateable but still separate from themselves.
In addition, the term synpath always describes the subject that a person identifies with, but never describes the person themselves.