Lightness is a term that can refer to a variety of different concepts. In this crossword, the solutions all relate to a lightheartedness or lack of seriousness. Friviolity is defined as behavior that is not serious or sensible, FLIPPANCY is a lack of respect or seriousness in speech or behavior, PRANK is a mischievous trick or JOKE, JOKE is an amusing story or remark, LEVITY is a lack of seriousness or steadiness, and AIRINESS is a lightness or delicacy. Together, these words all point to a concept of lightness or lack of seriousness.