To protect something, especially an environmentally or culturally important place or thing, from harm or destruction. Efforts are being made to conserve the rainforest for future generations.
To use resources carefully in order to prevent waste and ensure they last longer. We need to conserve water during the drought by taking shorter showers.
(Physics, mathematics) To remain constant in a closed system, or to cause a physical quantity to remain constant. In an isolated system, total energy is conserved.