Mostly on "western" or "cowboy" TV shows, I used to hear the word "plumb" used as an adverb, as in "That feller (fellow) is plumb crazy," meaning very crazy. Or "I'm plumb full," meaning "I can't eat another bite." Only occasionally did I hear such a phrase in real life.
According to the OED online and other sources, "plumb" got to mean "very" because it was related to a level or "plumb" line--a line that is (in theory) absolutely level . So plumb = absolutely or at least very. But of course people got it confused with "plum," as in the fruit, and indeed the first citation with regard to the American colloquialism "plumb [crazy]" cites "plum":
1588 T. HUGHES Misfortunes Arthur II. iv. 21 The mounting minde that climes the hauty cliftes..Intoxicats the braine with guiddy drifts, Then rowles, and reeles, and falles at length plum ripe. 1738 J. J. BERLU Treasury Drugs Unlock'd (ed. 2) 67 The best [jujubes] are plumb-full of Pulp, and come from Italy.
There's even a blog out there called "Plum Crazy," which bills itself as the home of the Vast New York Yankee Conspiracy." It's at www.houseofplum.com.
As late as 2002, according to the OED online, "plum" was used to refer to "testicle" in a piece of American fiction. I didn't expect that one, but I guess it makes some sense.
More interesting to me is that "plum" (in England) used to refer to the sum of 100,000 pounds--that is, a monetary "fortune," as the OED notes. I wonder if P.G. Wodehouse, whose nickname was apparently "Plum," earned a plum from his writings. If so, he did indeed earn it with all the laughs the writing generated.
This has all been a shamefully circuitious introduction to a poem that's focused on one kind of plum, the green gauge plum, which is rather large, has a firm "meat," stays the color green even after it ripens, and happens to be my favorite plum, just in case anyone asks.
Walking on the gray road toward the place
where the yellow school-bus stopped,
I used to pause and pick a green-gauge
plum to add to my silver lunch-pail, which
I took to school every day. That had to have
been in Septembers. Nobody else seemed
to harvest the plums, which hung on trees
that no one tended to. So little pleased me
then. So much surrounded me: mountains,
water, air, and time, for instance. Also immense
pines and cedars. --Interesting how we learn
to want mostly the wrong things in great
quantities. One ripe green plum tucked into
a metal box next to a lunch my mother had wrapped
in wax-paper, a bit of wire holding the Thermos
full of milk in place: these particularities pleased
me. I picked the plum and packed it away
and had the feeling it was treasure.
Copyright 2009 Hans Ostrom