as an adjective, 'extinct' describes a species that no longer has any living members. It can also refer to something that is no longer in existence or has been extinguished.
The dodo bird is extinct.
That volcano is extinct and hasn't erupted in thousands of years.
Some ancient languages are now extinct.
'extinct' is different from 'endangered.' An endangered species is at risk of becoming extinct but still has living members. Avoid using 'extinct' to describe things that are merely outdated or less popular; it's a strong word that implies a complete cessation of existence.
while 'extinct' is not commonly used as a verb in modern English, in older texts or in a more archaic sense, it can mean to extinguish or put out.
He extincted the candle before leaving the room. (Note
This usage is archaic. In modern English, we'd more likely say 'He extinguished the candle.')
The traditions were extincted over time. (Again, this is an older usage. Today, we'd say 'The traditions died out over time.')
the verb form of 'extinct' is rarely used in contemporary English. Instead, 'extinguish' is the preferred verb for this meaning. Using 'extinct' as a verb can sound archaic or poetic, so it's essential to be aware of the context and audience.