se ‧ cede /sɪˈsiːd/ BrE AmE verb [intransitive] formal
[ Date: 1700-1800 ; Language: Latin ; Origin: secedere 'to go apart' , from cedere 'to go' ]
if a country or state secedes from another country, it officially stops being part of it and becomes independent OPP accede
secede from
By 1861, 11 states had seceded from the Union.