Has both an active sense ('to commit genocide,' usually
灭种 + a victim group) and a passive/intransitive sense ('to go extinct'). The full term
种族灭绝 (zhǒngzú mièjué, 'genocide') is the modern legal/journalistic standard;
灭种 is shorter and more historically loaded - it appears heavily in late-Qing/Republican-era nationalist writing about
亡国灭种 ('national subjugation and racial extinction').