Definition of "mediocre"

The mediocre teacher tells. The good teacher explains. The superior teacher demonstrates. The great teacher inspires.

1968, William Arthur Ward, Thoughts of a Christian Optimist‎, Droke House

Of the hundreds of inferior poets, who are continually offering their sonnets and addresses to the Moon, (or to the public instead of that luminary,) Wade, Barton, Wiffen, and Bailey, are the most conspicuous. Wade is a new aspirant, but gives strong prognostications of genius. Barton and Bailey are above the mediocres, and Wiffen tolerable.

1825, “Present State of Literature”, in The Gentleman's Magazine‎, volume XCV, second part, page 197

After this lecture, how do the mediocres feel? They probably feel indifferent or mad. Perhaps they were not even paying attention. The question is, are they more likely to be in the hallway tomorrow? Probably not.

2014, Todd Whitaker, Dealing with Difficult Teachers, Third Edition, page 84