Adiabatic System:
An adiabatic system is a thermodynamic system that does not allow the transfer of heat across its boundaries. In other words, it is a system that is completely insulated, preventing any heat exchange with its surroundings. The term "adiabatic" comes from the Greek words "a" meaning "without" and "diabainein" meaning "to pass through."

Heat Transfer:
Heat transfer is the exchange of thermal energy between two objects or systems that are at different temperatures. It can occur through three main mechanisms: conduction, convection, and radiation. Conduction is the transfer of heat through direct contact between two objects. Convection is the transfer of heat through the movement of a fluid, such as air or water. Radiation is the transfer of heat through electromagnetic waves.

Boundary between the System and Surroundings:
In thermodynamics, a system refers to a specific region or set of objects under consideration, while the surroundings encompass everything outside the system. The boundary between the system and surroundings is the interface that separates the two.

Explanation:
In the given question, the system being referred to is one that does not allow the transfer of heat across its boundary with the surroundings. This means that the system is completely insulated, preventing any heat exchange with its surroundings. Such a system is called an adiabatic system.

Significance of Adiabatic Systems:
Adiabatic systems are often used in various applications where it is desired to minimize or eliminate heat transfer. For example, in the field of thermodynamics, adiabatic processes are used to analyze the behavior of gases in engines or compressors. By preventing heat exchange with the surroundings, the adiabatic assumption simplifies the analysis and allows for the calculation of important parameters such as temperature, pressure, and volume changes.

Conclusion:
In conclusion, an adiabatic system is a thermodynamic system that does not allow the transfer of heat across its boundaries with the surroundings. It is completely insulated, preventing any heat exchange. Adiabatic systems are important in various applications where minimizing or eliminating heat transfer is desired.