A power of veto possessed by every member of a legislative body, specifically that which existed under the later Polish monarchy in the 18th century. Hence: any power of veto.
liberum veto/ˌliːbərʊm ˈviːtəʊ/ /ˌlʌɪbərəm ˈviːtəʊ/
Mid 18th century. From post-classical Latin liberum veto from classical Latin līberum, neuter of līber free + vetō.