What is "desysopped"?

http://en.wikipedia.org/wiki/Wikipedia:Rollback_feature:

Standard rollback may only be used in certain situations – editors who misuse standard rollback (for example, by using it to reverse good-faith edits in situations where an explanatory edit summary would normally be expected) may have their rollback rights removed. Since rollback is part of the core administrator tools, an admin could theoretically be desysopped in order to remove those tools.

I couldn't understand the last sentence, I was wondering what's "desysopped" ?

It means "to have administrator privileges removed from their account".

Another name for an administrator is a "sysop" (short for System Operator), so it's a case of verbing. It would probably be clearer if they hyphenated it: de-sysopped.