1. Well-defined, easily distinguishable boundaries or borders between areas, concepts, or entities
The two countries have clear boundaries marked by mountains and rivers.
Os dois países têm fronteiras nítidas marcadas por montanhas e rios.
2. Precise demarcation lines that are unambiguous and clearly visible or conceptually distinct
In mathematics, we need to establish clear boundaries between different sets.
Em matemática, precisamos estabelecer fronteiras nítidas entre diferentes conjuntos.