D defs.my
Entry 3 senses Webster, 1913

Disunion

/dĭs-yo͞on'-yən/ · Dis·un·ion · IPA /dɪsjˈuːnjən/
01 n. The termination of union; separation; disjunction; as, the disunion of the body and the soul.
  1. 1.
    The termination of union; separation; disjunction; as, the disunion of the body and the soul.
  2. 2.
    A breach of concord and its effect; alienation.
    “Such a disunion between the two houses as might much clou� the happiness of this kingdom.” Clarendon.
  3. 3.
    The termination or disruption of the union of the States forming the United States.
    “I have not accustomed myself to hang over the precipice of disunion.” — D. Webster.