Jesting, frivolous, not serious. Cf. game, n. 3. Obsolete. rare.

Of a person or mental faculty: inclined to jesting or levity; light-hearted or playful in temperament, thought, or manner of expression; (also)…

Light-hearted, frivolous, flippant.

tending to revelry; enlivening, exciting to levity.

Displaying unbecoming levity in the consideration of serious subjects or in behaviour to persons entitled to respect.

(un-, prefix1 affix 1.)

(a) south-western dialect (see quots.). Hence in standard use: glib, flippant. (b) U.S. Voluble.