A contested term is usually factionally defined. That is, a faction might agree internally on what it means, but to outsiders their definition may be regarded as biased and ideological. The glossary makes note of many of these.
As a simple example, "the left" usually cares more about safety than closure, and "the right" puts its priorities the other way around. Thus they rarely or never agree on fairness. Also, "the left" usually sees evil as the result of a lot of ignorance, especially by "the right". But "the right" usually sees it as something intentional they can "punish".
It is foolish in the extreme to attempt to define a contested term too early, or at all, if there is faction tension on it's meaning and what actions it must guide. Failure to deal with this perfectly will lead to mindless forking or anti-leverage, at best:
"Many activists doubt the importance of definitions and the understanding of basic concepts before calling for action. They are intent on movement instead. But if you don't think through the meaning of what you stand for, you will end up doing the opposite of what you assume. Ill-defined ideas, even propelled by good will, can undercut common ground... by corrupting understanding from within." - John McMurtry