Толковый словарь английского языка Oxford English Reference - conservation

n. preservation, esp. of the natural environment. Phrases and idioms conservation area an area containing a noteworthy environment and specially protected by law against undesirable changes. conservation of energy (or mass or momentum etc.) Physics the principle that the total quantity of energy etc. of any system not subject to external action remains constant. Derivatives conservational adj. Etymology: ME f. OF conservation or L conservatio (as conserve)