the preservation and careful management of the environment and of natural resources | a basic truth or law or assumption |
(physics) the maintenance of a certain quantities unchanged during chemical reactions or physical transformations | a rule or standard especially of good behavior |
an occurrence of improvement by virtue of preventing loss or injury or other change | (law) an explanation of the fundamental reasons (especially an explanation of the working of some device in terms of laws of nature) |
| a basic generalization that is accepted as true and that can be used as a basis for reasoning or conduct |
| a rule or law concerning a natural phenomenon or the function of a complex system |
| rule of personal conduct |