What does Authentic mean?

Describes both original denim qualities and stone and enzyme wash optics.

Heddels explains Authentic

It also became a marketing buzzword during the early 1990’s, whereby the characteristics of authentic denim are traditional fabric weaves and styling details.

Additional Resources

An example of authentic slubby, Japanese selvedge (Pure Blue Japan):

Slubbiness - Pure Blue Japan XX05 (source: PBJ)