noun
this mortal world; this transient life; one's present existence
Literary and poetic term emphasizing the fleeting, insubstantial nature of worldly existence, often contrasted with spiritual or eternal truths. Common in classical Japanese literature and Buddhist-influenced writing.
うつせみの世ははかないものだ。
This mortal world is fleeting.
彼はうつせみの身を嘆いた。
He lamented his transient existence.
noun
Refers literally to the empty exoskeleton left behind when a cicada molts. The word 'cicada' itself can also be meant, but the shell sense is more distinctive. The kanji 空蝉 directly suggests this image.
木の幹に空蝉がくっついていた。
A cast-off cicada shell was stuck to the tree trunk.
夏になると、庭で空蝉をよく見かける。
In summer, I often see cicada shells in the garden.
Originally referred to the cast-off shell of a cicada (空蝉). By extension, it came to be used as a metaphor for the fleeting, empty nature of human existence in classical Japanese literature, influenced by Buddhist concepts of impermanence. The kanji are ateji (phonetic) for the native Japanese word うつせみ.