Noun
the gracefulness of a person or animal that is quick and nimble
the cheerful feeling you have when nothing is troubling you
the trait of being lighthearted and frivolous
Source: WordNetO fair, false city, thou gay and gilded harlot! Wo for thy wanton heart, wo for thy wicked hardness! Wo unto thee, that the lightsomeness of life, beneath Italian suns, Should meet the solemnity of death, in a sepulchre so foul and fearful! Martin Farquhar Tupper