extinct
No longer in existence or living.
Adjective
This term carries a heavy sense of finality and permanence. It is most frequently associated with biological species that have vanished from the earth, evoking a feeling of loss or scientific curiosity. It suggests a total disappearance where there is no possibility of natural recovery.
Outside of biology, the word describes things that have completely died out, such as a volcano that will never erupt again or a custom that is no longer practiced. It differs from words like vanished or disappeared, which might imply a temporary state or a mystery, whereas extinct implies a verified, terminal end.