There are, of course, many ethical and health controversies surrounding vegetarianism in all its different forms, but we wanted to know – where did the words come from? Who invented "veganism"?

Vegetarianism has been around for a very long time. Some historians date it back to Ancient Greek philosophers, and religious sects of Buddhism and Hinduism have encouraged vegetarianism for hundreds of years. However, the word itself came into common usage in the 1830s. During this era, vegetarianism was associated with religious conservatives, some of whom also campaigned for the temperance movement to ban alcohol. (To this day, the Church of the Seventh-Day Adventists encourages a vegetarian diet.)

It is not completely clear who invented the word "vegetarian." It may have been the founders of the British Vegetarian Society in 1847. Regardless, its linguistic roots are very clear. The Latin word "vegetābilis" meant "lively or animating" and came to describe foods that made one lively or animated. The suffix "–arian" changes an adjective into a personal noun, as in librarian or veterinarian. From the 1840s onward, the word was in common English usage. (What actually makes a vegetable? Or a fruit? Learn more.)

Why "vegan" though? Where did that short word that connotes radical vegetarians come from? Donald Watson, founder of the Vegan Society, coined the word "vegan" in 1944 as a statement against vegetarians who ate dairy products. He took the first and last letters of the word vegetarian to create his orthodox version of vegetarianism. Today, as many as 10% of American adults say they follow a vegetarian-inclined diet, but only 1% of them are strict vegans.

Most people who describe themselves as vegetarians are technically lacto-ovo-vegetarians; that is they eat eggs and milk. If you want to get really specific in describing your diet, you could use some of these terms: pollotarians (if you eat chicken, but not meat from mammals), pescetarians (if you eat fish), freegan (if you eat food only when it's free).

Recently, a new word has entered the dietary lexicon: flexitarian. Though the term dates was invented in the 1990s, only in the past few years has it acquired common currency. The first flexitarian cookbook came out in 2008. Celebrity chef Mark Bittman advocates for a "plant-based diet" meaning one that focuses on plants but can include a little meat.

Michael Pollan's book The Omnivore's Dilemma uses a different nomenclature to talk about similar issues. By calling us "omnivores," Pollan suggests that we should not be herbivores (or carnivores, for that matter). The language he uses closely resembles the words that biologists use to talk about animals. Owls are carnivores; rabbits are herbivores. As with most attributes, though, we prefer to have different adjectives to describe the same behavior in animals and in humans.