Definition

When people speak and argue for hours it is often because they do not have a clear and common understanding of what they are talking about.

This at times happens in Buddhism. (Believe me, I was there...)

Clear definitions allow everybody to  be on the same page when discussing or reading about an issue.

Tibetan Buddhism defines mind as what distinguishes sentient beings from rocks or trees or bodies of water. Mind is that which grasps - or rejects - something external. It is characterized by a discriminating awareness or a sense of duality.

 "What is the mind? It is a phenomenon that is not body, not substantial, has no form, no shape, no color, but, like a mirror, can clearly reflect objects."

Lama Zopa Rinpoche