accesión; accession (and the verbs acceder and to accede)

These terms are cognates when, for example, they refer to the attainment of a dignity or rank: “the King’s accession to the throne” (la accesión al trono del Rey); “Elizabeth II acceded to the throne in 1952” (Elizabeth II accedió al trono en 1952). Likewise, in property law contexts accesión is “accession” when it denotes the acquisition of title to property by accession (adquisición de la propiedad por accesión), defined as a “mode of acquiring property by which the owner becomes the owner of any addition by growth, improvement, increase or labor” (Merriam-Webster).

However, accesión and accession are false cognates when “accession” refers to the act of becoming a party to a convention or treaty. In that sense “accession” is more appropriately translated as adhesión, as in “Spain’s accession to the EC Treaty” (la adhesión de España al Tratado de la CE) or “Member States that have acceded to the European Union” (Estados miembros que se han adherido a la Unión Europea).

(For additional meanings of adhesión and adhesion, see here.)