They speak of "direct democracy," which seems to resist direct definition.
More than any opera that comes to mind at the moment, "Onegin" stands or falls on the creation of moods that resist definition in prose.
Whilst most user groups can be identified with relative ease, the various types of material or service often resist clear definition.
Joel Fisher's slender sculptures resemble trees or figures but they resist exact definition.
The mercurial landscape of "The Tempest" also resists definition.
It is easy to see some such 'addictions' as excuses, especially as the term resists strict definition.
Then she does her best to describe an exhibition that seems to resist definition.
"Ballet," "dance" and "choreography" resist easy definition, in part because the arts to which they refer are constantly developing.
It's also a style that resists easy definition.
Postmodern literature, like postmodernism as a whole, tends to resist definition or classification as a "movement".