denique

Denique is an adverb with two jobs. It closes a list, the last step after primum, deinde, tum, and it sums up an argument: "in short, in a word". English "finally" covers both, which is why the word is easy to read and hard to place.

Keep it apart from its neighbours. Tandem is "at last" with relief or impatience in it, the word you use when the waiting was the point. Demum is "only then, not before", pinning down the moment. Postremo is simply "last in the sequence". Denique is the least emotional of the four, and in Cicero it often means something closer to "or for that matter", piling on a final example after everything else has failed to convince.