1.Definition: (of e.g. volcanos) permanently inactive

"An extinct volcano"

2.Definition: being out or having grown cold

"Threw his extinct cigarette into the stream"

Related Adjective(s):out

3.Definition: no longer in existence; lost or especially having died out leaving no living representatives

"An extinct species of fish", "An extinct royal family", "Extinct laws and customs"

Related Adjective(s):nonextant