What is the meaning of Micronation?

A non-autonomous entity that claims to be a sovereign state and mimics the actions of a state (with varying degrees of seriousness), but lacks any legal recognition and exists only on paper or in the mind of its creator; a micronational entity.

Synonym of microstate (a country that has a very small population and land area).

A small nation (historically constituted, stable community of people, formed based on a common language, territory, economic life, ethnicity and manifested in a common culture).

Source: wiktionary.org