Epistemic status: provisional.
What is a body? A person has a body -- perhaps a person is a body in the sense that what is truly and always your body is you.
A person can be affected by external things through their body. I can be affected in a powerful way by something striking my body. Also my body responds to my will. As I type, my fingers are mostly faithful to my personal intentions. If my fingers use the "backspace" key, they are more faithful in the end. I can move many parts of my body if I want to. But not all. I can't consciously cause peristalsis, or a heartbeat, for instance.
Loosely, roughly, then, a body is that which is a way for external beings to affect me, and through which I can affect myself, or external beings.
If we consider the world of material objects, the body is that which has arms, legs, hands, and feet, and so on. But if we consider the world of consciousnesses, then everything that I can see can affect me, and I can affect many things in my experience. Thinking simantically, everything that I perceive, I alter (in some sense; to some extent) so that it has the meaning that I see in it. By looking attentively at something, I can make it mean something to me, though what it means is spoken to me in accordance with who I am, by another. So then everything that I, personally, am consciously aware of is part of my body. The physical body has parts that are more, or less, in subjection to my preferences, and so it is with my experiences.
My experience body, then, is the body of all of my experience in a moment. I have it, and it is me, in analogy to how from a materialist point of view, I have a physical body, and am a physical body.