This, Metaphor and other forms of the word, are not so much terms used with a special meaning in Tom Campbell's My Big TOE as that it is pointed out here that all words are metaphors. There is no absolute meaning for words and all concepts arise from random meaninglessness at base. This is inherent to the nature of a VR and the nature of the LCS and frequently needs to be considered in any in depth discussion.
Metaphor and its cognates are defined in the Merriam-Webster on line dictionary as follows:
Definition of METAPHOR
1: a figure of speech in which a word or phrase literally denoting one kind of object or idea is used in place of another to suggest a likeness or analogy between them (as in drowning in money); broadly : figurative language — compare simile
2: an object, activity, or idea treated as a metaphor : symbol 2
— met·a·phor·ic or met·a·phor·i·cal - adjective
— met·a·phor·i·cal·ly - adverb