Before it was the trade name of check-balancing software and a loan company, "quicken" was a real word, though one rarely seen.
My first and only encounter with it was in the context of formal, corporate prayers said in church services. "Quicken our hearts, we pray" was a common phrase, one I liked, but it seemed a bit odd. Make our hearts beat faster?
No, make our hearts alive, as in Ezekiel 36:26. I later learned that before it was another way to say fast, quick meant living.
The Quick and the Dead isn't just a clever title for a western flick. The phrase originates in three passages in the King James version of the New Testament and is well known from the Apostles Creed. In all those instances it refers to Jesus judging the living and the dead. In the movie title then, we, and undoubtedly the film's creators, recognize the double meaning, but the two meanings amount to the same thing; quick means alive - especially for a gunfighter.
Other words begin to make sense when we know the archaic meaning of quick. The quick is the living tissue under the fingernail, and where we get the phrase "cut to the quick." Yeah, it hurts. Quicksand seems to trap its victim with purpose, like a living predator. And to anyone who has ever rolled mercury around in their hand (back before such a reckless act would have the hazmat squad whisking you into quarantine and stretching yellow caution ribbon around your house), it's easy to understand why quicksilver isn't just the name of a totally awesome Kevin Bacon movie.