Lewis & Short

dēcessus, ūs, m. [decedo], a going away, departure (opp. accessus—good prose).

  1. I. In gen.: post Dionysii decessum, Nep. Tim. 2, 3.
  2. II. Esp.
    1. A. The withdrawal, retirement of a magistrate from the province he has governed (in Cic. oftener decessio): post M. Bruti decessum, Cic. Phil. 2, 38; so Cael. ap. Cic. Fam. 8, 10 fin.
    2. B. Pregn., decrease, disappearance, departure: aestūs, the ebbing, subsidence, Caes. B. G. 3, 13; Nili, Plin. 18, 18, 47, § 168: febris, Cels. 3, 12: morbi, Gell. 4, 2, 13.
      1. 2. Decease, death: amicorum decessu plerique angi solent, Cic. Lael. 3, 10; cf.: EX DECESSV L. CAESARIS, Cenot. Pis. ap. Orell. Inscr. 643.