Noah Webster's New International Dictionary of the English Language

1. (n.) The quality or state of being round in shape; as, the roundness of the globe, of the orb of the sun, of a ball, of a bowl, a column, etc.

2. (n.) Fullness; smoothness of flow; as, the roundness of a period; the roundness of a note; roundness of tone.

3. (n.) Openness; plainness; boldness; positiveness; as, the roundness of an assertion.