1. A border or boundary between territories, states, or regions that changes position or control over time due to political, military, or geographical factors
The fluctuating frontier between the two nations shifted several times throughout history.
A fronteira flutuante entre as duas nações deslocou-se várias vezes ao longo da história.
2. In historical context, especially regarding American westward expansion, the moving boundary of settled territory advancing into unsettled areas
The American fluctuating frontier represented the edge of European settlement advancing westward.
A fronteira flutuante americana representava a margem do assentamento europeu avançando para o oeste.
3. A metaphorical boundary that constantly changes in scope, definition, or location
The fluctuating frontier of artificial intelligence continues to expand.
A fronteira flutuante da inteligência artificial continua a expandir-se.