Brain matter is a term used to describe the physical components of the brain, such as neurons, glial cells, and other tissues. The two crossword solutions for this term are 'IDEA' and 'obex'. IDEA is a noun that refers to a thought or concept, while obex is a Latin word meaning 'BARRIER' or 'HINDRANCE'. Together, these two words can be interpreted to mean that the physical components of the brain can act as a BARRIER or HINDRANCE to the formation of ideas.