Exothermic
A transformation which releases energy is said to be exothermic.
This energy can be given up to the external medium. If, however, the system cannot release the energy of an exothermic transformation its temperature will increase.
Endothermic
A transformation which absorbs energy is described as an endothermic process.
This energy can come from outside the system.
If the energy cannot come from an external source, the absorption of energy by the system will resulting in cooling.