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apparently coined in French by Leibnitz in 1692; attested in English from early 18c. as conservatio virum vivarum or partially nativized versions of it. The exact phrase is attested from 1853.
conservation of energy |
A principle stating that the total energy of a closed system remains constant over time, regardless of other possible changes within the system. It is related to the symmetry of time invariance. See also invariance, thermodynamics.