ephemeral

An annual plant with a very short life-cycle, usually producing several generations in a single season. Many weed species are ephemeral, as are desert plants which experience very short favourable seasons.

An ephemeral waterbody is a creek, stream, river, pond or lake that only exists for a few days following precipitation or snowmelt. Examples of ephemeral streams are the Ugab River in Southern Africa, and a number of small ephemeral watercourses that drain Talak in northern Niger. Lake Carnegie in Western Australia and Lake Cowal in New South Wales are ephemeral lakes.

Ephemeral can also be used as an adjective to refer to a fast deteriorating importance of an object to a person. A sensation which is felt by a person for a certain period of time before needing replenishment can be referred to as ephemeral.