A particular sort of misunderstanding is a disagreement on the definition of certain terms. Similarly to agreements, the mediator can name a term to define. The debaters go through a process until they find a definition or set of definitions that they agree on, for the purposes of the given debate. They don't have to agree that it is a proper definition, just that it is useful for the given debate, and that no useful definitions for the term are being neglected.

If both debaters agree on the same definition, and one debater uses the term to mean something else, the mediator should then step in and tell the debater to restate his or her point, using the term correctly (or just avoiding the use of the word). Also, after a term is defined, subsequent debate posts containing the term will turn into a handy mouseover tooltip that shows the definitions.

Guidelines for defining words

Phrasing

Phrase your definitions as if it were a dictionary entry. For instance, when defining "home" instead of saying "a home is a place where somebody lives", simply say "a place where somebody lives".

For the purposes of the debate

Keep in mind that the definition(s) for a term are for the purposes of the debate. You don't have to agree that these are the proper definitions, and you should allow for definitions that you don't find useful but that the other debater does.

Reject "unthinkable" definitions, but not "impossible" ones

The definition shouldn't have to be something that you think is possible, in just has to be thinkable. For instance, if Communism was defined as "a system wherein the means of production are collectively owned", and you didn't believe that this system is ever realizable, but you could at least imagine it working, you should allow it. Just as long as, when the topic is being discussed, it's clear to you what the other person is referring to. On the other hand, if your understanding of ownership is such that you can't comprehend more than one person owning the same thing, and you wouldn't be able to have a sensible debate as a result, then it would be appropriate to reject it.

If you want to make it clear that you don't believe a certain definition is possible to realize, leave it as a note, and the mediator may make a subdebate on the topic.