accession /ækˈsɛʃ.ən/noun 11verb 1forms 3 noun11 •A coming to; the act of acceding and becoming joined. •The act of coming to or reaching a throne, an office, or dignity.This is the 6 ft. 4-6-0 engine No. 8301, Springbok, the second design produced by Mr. Edward Thompson since his accession to office as Chief Mechanical Engineer. — 1943 •The act by which one power becomes party to engagements already in force between other powers. •Increase by something added; that which is added; augmentation from without.The only accession which the Roman empire received, during the first century of the Christian Aera, was the province of Britain. — 1776 •Such augmentation that adds to the collections of a museum or archive; a thing thus added. •A group of plants of the same species collected at a single location, often held in genebanks. •Agreement. •(Scotland) Complicity, concurrence or assent in some action. •Access; admittance. •A mode of acquiring property, by which the owner of a corporeal substance which receives an addition by growth, or by labor, has a right to the part or thing added, or the improvement (provided the thing is not changed into a different species). •The invasion, approach, or commencement of a disease; a fit or paroxysm. verb1 •To make a record of (additions to a collection); to add (something) to a collection (usually a museum's or archive's collection). formsaccessioned · accessioning · accessions