The mayfly (order Ephemeroptera) typically hatches, matures, mates, and dies within the span of a few short hours (though the longest-lived may survive a record two days); poets sometimes use this insect to symbolize life's ephemeral nature. When ephemeral (from the Greek word ephēmeros, meaning "lasting a day") first appeared in print in English in the late 16th century, it was a scientific term applied to short-term fevers, and later, to organisms (such as insects and flowers) with very short life spans. Soon after that, it acquired an extended sense referring to anything fleeting and short-lived, as in "ephemeral pleasures."

The young YouTube star's fame was ephemeral but surprisingly lucrative while it lasted.

 

"After winter, the garden comes to life with the planting of spring-blooming ephemeral bulbs such as naturalizing daffodils, crocus, tulips, snowdrops and hyacinths that appear before the tree canopy 'leafs out' and perennials burst forth…."

— The Parry Sound (Ontario) North Star, 6 Mar. 2019

Fill in the blanks to complete an antonym of ephemeral: _ e _ _ et _ _ l.