ephemeral

Lasting for a short period of time; not permanent.

In other words: transient, momentary, passing

• Her interest in the hobby was ephemeral, fading after a few weeks.

Existing for only one day, as with some flowers, insects, and diseases.

In other words: short-lived, one-day, transitory

• The mayfly is an ephemeral insect, living only a single day as an adult.

Usually dry, but filling with water for brief periods during and after precipitation.

In other words: seasonal, intermittent, temporary

• The desert has many ephemeral streams that flow only after heavy rains.

Something which lasts for a short period of time; a transient thing.

In other words: transient, fleeting thing, ephemeron

• The artwork was an ephemeral, meant to be enjoyed only for a moment.