1. Want of ornament; want of artificial show.

So modest plainness sets off sprightly wit.

2. Openness; rough, blunt or unrefined frankness.

Your plainness and your shortness please me well.

3. Artlessness; simplicity; candor; as unthinking plainness.

4. Clearness; openness; sincerity.

See ing then we have such hope, we use great plainness of speech. 2 Cor 3.