Exothermic is the release of heat. Exo as in exit to leave and thermos, the Greek word for heat. Endothermic is the absorption of heat. So if a chemical reaction is exothermic the reaction loses heat and it feels warm to you. If it is endothermic, it absorbs heat. If you are holding a beaker with an endothermic reaction, it will absorb the heat from you and therefore these re actions feel cool to touch!