entrenchment

"Linguistic structures are more realistically conceived as falling along a continuous scale of entrenchment in cognitive organization. Every use of a structure has a positive effect on its degree of entrenchment, whereas extended periods of disuse have a negative impact. Is there a some particular level of entrenchment that can serve as a non-arbitrary cutoff point in defining units? .... The absence of a sharp division between units and nonunits has the consequence that the scope of a grammar is not precisely delimited." (pp.59-60)

2.1.1