\Ac*ces"sion\, n. [L. accessio, fr. accedere: cf. F.
accession. See {Accede}.]
1. A coming to; the act of acceding and becoming joined; as,
   a king's accession to a confederacy.
2. Increase by something added; that which is added;
   augmentation from without; as, an accession of wealth or
   territory.
         The only accession which the Roman empire received
         was the province of Britain.          --Gibbon.
3. (Law)
   (a) 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). Thus, the owner of
       a cow becomes the owner of her calf.
   (b) The act by which one power becomes party to
       engagements already in force between other powers.
       --Kent.
4. The act of coming to or reaching a throne, an office, or
   dignity; as, the accession of the house of Stuart; --
   applied especially to the epoch of a new dynasty.
5. (Med.) The invasion, approach, or commencement of a
   disease; a fit or paroxysm.
Syn: Increase; addition; augmentation; enlargement.