An adiabatic system is one where no thermal energy (heat) moves across the boundaries (in practice, this is accomplished through the use of insulation, so this is often also called an "insulated" system).

Does perfectly insulated mean adiabatic?

An adiabatic process is one in which there is no heat transfer into or out of the system. The system can beconsidered to be perfectly insulated. ... It is the temperature that would be achieved by a flame in the absence of heat loss to the surroundings.

What does Insulated mean in thermodynamics?

It means that the system can't exchange energy with the surroundings; no heat can be added into the system or taken out of it. In other words, it is an isolated system.