UKs
UKs is not a standard or widely used term in official discourse. In most contexts, the country is referred to as the United Kingdom (UK). The plural form “UKs” may appear in informal writing or data labels, but it is ambiguous and can be misleading.
Historically, some writers have used the notion of “the United Kingdoms” to describe successive political unions
In contemporary usage, the conventional term is the United Kingdom, abbreviated UK. The plural “UKs” is rare