A metaphor is not merely a linguistic expression (a form of words) used for artistic or rhetorical purposes; instead, it is a process of human understanding by which we achieve meaningful experience that we can make sense of. A metaphor, in this "experiential" sense, is a process by which we understand and structure one domain of experience in terms of another domain of a different kind.
Mark  Johnson, The Body in the Mind: The Bodily Basis of Meaning, Imagination, and Reason
language, linguistics, meaning, metaphor, philosophy