When energy is unable to pass from a system to its surroundings, it's called thermal isolation or adiabatic.

Here's why:

* Thermal Isolation: This term emphasizes the prevention of heat transfer between the system and its surroundings. It implies a barrier or mechanism that blocks the flow of heat.

* Adiabatic: This term refers to a process where no heat transfer occurs between the system and its surroundings. It's often used in thermodynamics to describe a specific process, like an adiabatic expansion or compression.

In essence, both terms describe a scenario where the system's internal energy remains constant, as no heat can escape or enter.