It's fine to start with supplied definitions but if there is disagreement with them then the reasoning behind the definitions should be worked out. If there is then still no agreement then the discussion can end early.
For example:
Transitional Fossils.
If one is agrueing for or against the ToE then one should use that model (that of evolutionary biology) to derive a 'reasonable' definition of a transitional fossil (TF ).
The model says that a base population of animals will undergo a series of speciation events. At the end of a long chain of these we have different taxonomic categories that we see today.
The model suggests that two 'related' taxa today sprang from a base. Near that base the two taxa should be still pretty similar. In fact, it can take sometime before we decide the split has occured. The dino bird example shows that. (as does human and other primates).
Given that the more divergent animals are probably those which move into new niches -- e.g., flight for the dinosaurs but there old niches may (or may not) remain we would expect to see one branch develope new characteristics but the other branch (in the old niche) may stray less far.
Thus we expect a transitional to carry over some of the features of the original base but layer new ones on top. The one branch may lose features of the base faster than the other branch too but retain them for sometime.
To check this we would look for some fossils that are close to the apparent point of divergence. We'd expect to see two branchs (or more) that are both still close to the base but both with some differences.
We'd expect further to find (if we get lucky) later forms which show gradual further divergance from each other.
There is no reason at all why the model would expect large leaps. In fact, our understanding of genetics suggests that large leaps have got to be rather rare.
Can we derive a complete definition of transitional from this?
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