[…] isolects (ie systems of individual speakers), or lects. Each (iso)lect is the output of a grammar (which is part of a polylectal grammar), is invariant, and differs from the one immediately next to it with respect to a single feature or rule in the panlectal grammar.
- Romaine (1988), a pag.163

[…] isolects […] participate differently (ie earlier or later ) in an incipient rule change which is introduced at any given point in the spatio-temporal continuum.
- Romaine (1988), a pag.163