What is "cloud cuckoo land"

Imaginary city built in air, translating Aristophanes' Nephelokokkygia in "The Birds" (414 B.C.E.).

n. (alternative spelling of cloud-cuckoo-land English)

Cloud Cuckoo Land refers to a state of absurdly over-optimistic fantasy or an unrealistically idealistic state where everything is perfect. Someone who is said to "live in cloud cuckoo land" is a person who thinks that things that are completely impossible might happen, rather than understanding how things really are. It also hints that the person referred to is naïve, unaware of realities or deranged in holding such an optimistic belief.

Cockaigne, the land of plenty in medieval myth, can be referred to as the modern day cloud cuckoo land. It was an imaginary place of extreme luxury and ease where physical comforts and pleasures were always immediately at hand and where the harshness of medieval peasant life did not exist.