Disruption
Disruption is disturbance or problems that interrupt an event, activity, or process. In the wikisphere, disruption can be whatever is deemed to interfere with the wiki's mission. It is left purposefully vague lest there be instruction creep in which a complicated body of rules is created that is hard for users to master, and which might cause some good behaviors to be inadvertently prohibited or bad behaviors to be inadvertently left unprohibited. Of course, the same can happen without rules; a user can be blocked for good behavior or a user who behaved badly can be left unblocked, depending on the whim of whoever is making the decision.
If the norms favor construing broadly what is considered disruptive, then the definition of it also tends to become more and more hazy, and it becomes harder to predict what might fall under it. Taken to its extreme, almost anything that goes counter to the agenda of a dominant faction of users, sysops, etc. or the site owner could be considered disruptive, and thus the ability to avoid being blocked for disruption depends on making accurate predictions of what those in charge will or won't tolerate.
In some situations, a sysop will warn a user that his behavior is disruptive and tell him to stop. But of course, the warning may or may not represent the will of the wiki, as there may be a higher authority such as the site owner, bureaucrats, other sysops, or the community that can overrule the sysop. Under such circumstances, asking for the opinion of the site owner, or of the community, on the sysop's behavior could itself be considered a form of trolling or other disruption, depending on the wiki norms. On those types of wikis, then, it becomes important to either err on the side of caution or be very good at predicting what sysop actions will be upheld by higher authority.