Noun; commonly used in the expression fruit and veg. Vegetable, but also a vegetable or produce stand or market, or vegetarian food, a vegetarian dish, or a vegetarian, as in this Urban Dictionary exchange:
“Do you want to go to Steak Hut?”
“No, I’m veg.”
A couple of points worth noting. The OED’s first citation of this veg is from an Arnold Bennett novel in 1898, and there is this from P.G. Wodehouse in 1940: “The fruit and veg. dept has just given of its plenty.” (That is the last cite with a period to indicate abbreviation.) The verb veg or veg out, to (often facetiously) indicate hanging out in a more or less vegetative state, seems to have originated in the U.S., the OED first citing it in a 1980 Washington Post article, but quickly spread to the U.K.
The traditional U.S. nickname for vegetable is, of course, veggie, which inspires some general comments about U.S. and British differences regarding diminutives and/or abbreviations. In short, the Brits seem to want to shorten the original word, while we elongate it. Thus, over there, your vacation becomes hols and instead of brilliant you can just say brill. To them, Reginald becomes Reg; to us (in the rare cases when we know a Reginald), he is Reggie. American Williams become Billys or Willies; British ones are Will or (if you really want to express fondness) Wills. On the other hand, the morning meal is brekkie (beautifully illustrated in the alliterative headline from The Sun BIKINI BATTLE OF THE BREKKIE BABES) and Russell Brand called his autobiography My Booky Wooky. I guess the bottom line is that the Brits really like their nicknames.
[Fritz] Haeg, who lives in a geodesic dome in the easterly neighborhood of Mt. Washington, was talking about his ongoing project Edible Estates, which encourages people to tear out their lawns and plant fruit and veg instead. (Dana Goodyear, Letter from Los Angeles, blog, the New Yorker, July 25, 2008)/Miller Park, Milwaukee, Racing Sausage Kabobs: These are the creation of a fan in a concession contest. Courtney Ring decided to poke a couple of skewers through the famed Klement’s Racing Sausages (dog, brat, chorizo, Polish, and Italian) and grill them with some veg. (Philadelphia Inquirer, April 10, 2011)
notoneoffbritishisms.com 
Hi, I’m not sure where those Urban Dictionary entries originate from, but in the UK ‘veg’ would only be used to describe vegetables. For anything or anyone vegetarian we’d instead use ‘veggie’.
Just a few months ago we had American relatives coming over and, in preparation for a Welsh banquet we were planning for them, we emailed them asking if they were veggies. We couldn’t understand why they were confused!
I love it. I’m getting the sense there are regional differences in the U.K. on this one, and would appreciate more data.
And by the way, this entry got me thinking about “mash” as diminutive of “mashed potatoes,” as in “bangers and …” There is evidence this is getting some U.S. traction, as in this sentence for an April 3, 2011, restaurant review in the Albany Times-Union: “Dark and succulent osso bucco was tarnished by overwhipped Potato-Bud-like mash.” (Note to U.K. readers wondering what a Potato Bud is: don’t ask.)
Me again [Scottish with English family] if someone asked me “are you veggie” I’d know that they were asking about my dietary habits. If they asked “are you veg” I’d think “WTF are you talking about?”. To me it sounds like the kind of thing you’d say when trying to wake someone up, to see if they were asleep or actually in a coma.
Isn’t Potato Bud basically Instant Mashed Potato? Does it taste all floury and yuck like the stuff you get over here? I know, I asked, sorry. No-one wants to think about reconstituted potato, I know.
P.S. I believe the shirt in the above picture is a kind of rule-proving exception. A bit like posters referring to an event “TONITE” not being a demonstration of the way people usually spell “tonight”, if that makes sense.
When I was at university, we used it as a verb, particularly with regard to our plans for Sundays. Let’s veg out meant that we would sleep late and after waking, do nothing except lounge around in a somnambulant manner, doing as little as possible. it did not mean heading to the Salad bar to gorge on mung beans and arugula.
I hope this comment reaches you. Otherwise, I’ll have wasted all this energy for nothing.
English descendents in South Africa use ‘veg’ as a verb and a noun, but never as an adjective. My visits to Great Britain indicate that ‘veg’ is only really used as a noun now.
I’ve also never heard someone say “I’m veg”. The noun form is strictly used to refer to vegetables.
When my partner returned from a trip to India a few years ago, he described the use there of “veg” and “non-veg” to refer to meals without meat and with meat, respectively. And I heard it in a similar context from one of my coworkers the other day. Must be spreading!
No regional variations that I’ve noticed, pretty universally over here “I’m a vegetarian” would be “I’m a veggie”. “Veg” is an abbreviation for “vegetable(s)”. Similarly, the vegetarian options on menus, or a vegetarian restaurant would be “veggie option / a veggie restaurant”.
Our equivalent of “potato bud” would be “smash”. And I can’t think of a more vile way to create something purporting to be mashed potato. But they have great TV ads. (or used to.)
There is also the verb ‘to veg’, meaning to slob about on your arse all day.
Can also be described as ‘veging out’, on the sofa and such.
“I’m a veg” = “I’m a vegetable”. “I’m a veggie” = “I’m a vegetarian”.
Why isn’t the short version of vegetable VEGIE?? Why an extra G