Old Single Meaning
The meaning, neither abstract nor concrete, neither literal nor figurative, which the source words of a language once possessed when man was still part of the primal unity of things. It is from these original meanings which those words that now have merely material references or abstract contents alike descended as a result of the evolution of consciousness.

The "error" of linguists, who routinely assume a development from simple, 'root" words, is the result, according to Barfield, of "supposing that life actually created language after the manner in which their logic constructed it. They mistook the elements for seeds and called them roots" (PD 82).

See in particular "Meaning and Myth" (PD 77-92).