Something that transfers thermal energy efficiently is called a conductor.
A conductor of heat is something that transfers thermal energy efficiently.
conductors
Heat transfers thermal energy efficiently from one source to another. The movement of particles when heated results in this efficiency.
conducter
An insulator
conductor
You're probably fishing for "conductor".
This is heating and cooling. Direct transfer from one solid to another is conduction. Transferring through fluids (liquids or gases) normally uses convection. and heat being projected through a space, usually as light or infra-red, is radiation.Heat is the term that defines something that transfers thermal energy efficiently.
insulator
Thermal energy poorly and slowly transfers in liquids
Thermal gradient.
A thermal conductor.
Radiation
thermal energy will always radiate to lower energy matter.