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1. To become extinct gradually, as of a group of people or animals. That species of birds will die out if we keep destroying its habitat.
2. To become outdated or obsolete. The prevalence of cell phones today has caused the use of landlines to die out.
1. Lit. [for a species or family] to perish totally because of the failure to produce offspring. l am the last one in the family, so I guess our line will die out with me. The owls might die out if you ruin their nesting area.
2. Fig. [for an idea, practice, style, etc.] to fade away through time. That way of doing things died out a long time ago. It died out like the horse and buggy.
Gradually become extinct, as in As technology advances, and Western culture spreads, many folk traditions are dying out . [Mid-1800s]
1. To become extinct: The dinosaurs died out millions of years ago. These tribal customs died out centuries ago.
2. To diminish and finally cease functioning or existing: With a few final flickers, the candles died out.