Primarily, we wanted to reduce the one-thing-per-merge calls, but also,
we want to reduce allocations overall, both from merge calls which will
duplicate the source hash and from string constants sprinkled
throughout.

Seemingly, defining a constant-style word list is not the ticket.  For
whatever reason, Ruby can't seem to figure out the list doesn't change,
and presumably is splating out all of the words and allocating them as
if they were declared right there.  Wahhhh.

Now we're using a straight up one-for-one constant definition of each
string, in a big constants file, where we freeze the strings on the
spot.  We then reference each constant directly at the callsite, which
was the original style and, ultimately, is the best for readability.