"Whisky is an alcoholic distillate from a fermented mash of grain produced at less than 190 proof in such manner that the distillate possesses the taste, aroma, and characteristics generally attributed to whisky, stored in oak containers (except that corn whisky need not be so stored), and bottled at not less than 80 proof..."
-The Code of Federal Regulations (Title 27)
Bluntly put, by today's definition, whisky is made by fermenting and distilling grain that, afterwards, may or may not spend time in an oak barrel. After that, the code blathers on about more titular designations, proof and percentage requirements and blending rules, before it states that Scotch, Irish and Canadian whisky are all awesome enough to abide by a different, independent set of labeling requirements for their products. In all those other countries, laws require the alcohol to age for at least three years in a barrel before they can call it whisky, unlike the American prescription, which is to age it for as long as you feel like. U.S. markets abide by the laws of those countries when defining their respective products, so if you call it "Single Malt Scotch whisky" and it doesn't conform to all the rules for such set forth in the UK, then you can't sell it as single malt Scotch in the United States either. We'll cover all the nitty gritty definitions later on, so don't pay too much attention here.
But what about India? Colonial invaders from the British Isles, taught the natives to distill whisky from molasses instead of barley. Does that make the spirit more rum than whisky? The way the feds define rum here in the US, yes, it is rum. Still, if I made a burrito with naan bread instead of a tortilla, I'd call it a naan burrito. All history considered, making whisky in a new world by changing the material you ferment is just about as traditional an approach as one could take towards making whisky. It's how the original, American bootleggers received the art, so this is what a lot of people call whisky in India. If we can label cassia as cinnamon and label a box of ordinary cornstarch as Arrowroot powder then, I think granting Indian Whisky its own declaration isn't completely incongruent with our current practices. However you feel about the issue yourself, the topic is one of contention for importers to tip-toe around. India ultimately lacks the same authority as the UK and Canada do to sell their spirits here.
And what about the Singleton of Glendullan: a spirit distilled from what tastes like a mash of fermented hooker and stray dog, aged in what must be a recently-repurposed sewer, watered down for bottling with beer-cooler drippings imported from the skankiest dive bars in Edinburgh? This "spirit" circumvents an even stricter set of local regulations and is legally labeled a single malt Scotch!!! Normal single malt whisky in Scotland has to be made from malted barley and aged in barrels made of wood... barrels that were not filled with diarrhea prior to being filled with alcohol. If this is a whisky... well... I'm just confused.
More food for thought: Does adding flavoring disqualify a spirit from being called whisky? What if you tainted it with traces of other beverages? Is it still whisky when I add enough sherry to taste it, then filter out half of the proteins and dye it a caramel color? Some Scotch distillers put their whisky into barrels that have traces of other beverages still in them. Some even "chillfilter" their spirit and add caramel coloring. If that's whisky, what about after I mix it with a splash of cola, water or (blech) ice? What then? How far should the definition reach? I have no easy answers for you, but if you read all of this and follow our recommendations, by the end of it all, you should be able to tell people, with authority, exactly how nebulous the subject is. That's the best anyone can hope for. So what is the first thing you should be taking away from all of this rambling? That there are not only a mind-boggling number of rules to keep track of, but that there are an equally large number of exceptions and possibilities that fly in the face of tradition, as well. There are, of course, traditions and regulations that are fun to explore and worthwhile to preserve, but ultimately, it is amazing flavor that trumps them all!
Next: How to Make Whisky