1.
this world; this transient life
The everyday world and its troubles, seen as fleeting. From the Buddhist idea of the 'sorrowful world' (憂き世), later written 浮世.
2.
the floating world (of Edo-period pleasure)
The world of fashion, theatre and the pleasure quarters in Edo-period cities, as in 浮世絵 and 浮世草子.
Etymology
Originally 憂き世 (the sorrowful world). In the Edo period the spelling 浮世 (floating world) took over, and the sense shifted toward the pleasures of the moment.
Common expressions
Usage
Sense 1 is literary or old-fashioned in speech; it survives mainly in set phrases.