n. 不存在的事, 无, 不存在的东西

[ noun ]
the state of not existing
<noun.state>

Nonexistence \Non`ex*ist"ence\, n.
1. The state of not existing; absence of existence; the
negation of being; -- usually used with reference to
existince in the real world, or logical possiblity; as,
the nonexistence of vaporware does not go unnoticed long.
--A. Baxter.

Syn: nonentity[1].
[1913 Webster +PJC]

2. A thing that has no existence. --Sir T. Browne.