Definition of ex post facto in English:

ex post facto

Syllabification: ex post fac·to
Pronunciation: /ˌeks pōst ˈfaktō
 
/

adjective& adverb

With retroactive effect or force: [as adjective]: ex post facto laws

Origin

erroneous division of Latin ex postfacto 'in the light of subsequent events'.

Definition of ex post facto in: