A negative side effect; an undesirable or unexpected consequence.
A declined offer in a sales transaction when acceptance was presumed.
An impromptu guest used to fill in for another guest spot who is a no-show or who has cancelled last minute.
The person who declines such an offer.
The event of small airborne particles falling to the ground in significant quantities as a result of major industrial activity, volcano eruption, sandstorm, nuclear explosion, etc.
The particles themselves.
A good aspect of a mostly bad event.