When buzzwords go green

With "green tech" currently the hottest topic among everyone from venture capitalists to A-list actors, you have to know what you're talking about. So, we've assembled a handy cheat sheet of the most important eco-jargon so you never make the mortal error of confusing "clean-burning" with "zero-emissions." We also included cultural references where it seemed appropriate. If you want more substantial (or less snarky) definitions for any of these, just remember: Google is your friend.

biodiesel: A variety of biofuel (see definition), specifically diesel fuel manufactured from vegetable matter rather than nonrenewable fossil fuels.

biofuel: This refers to all variety of fuels, both gas and liquid, that are derived from biomass--and hence are renewable, as opposed to fossil fuels. The usual suspects are wood, ethanol (derived from corn), and the mouthwatering new one, french fry grease. Other biofuels come from sources that are somewhat less yummy: landfill gas, cow manure, sludge, and fish oil, for example.

carbon: Such a naughty word these days. It's been somewhat unfairly demonized, considering carbon (element number 12 in the periodic table) is the third-most common element in cells and is absolutely crucial to the existence of life on earth. That said, carbon dioxide--you know, what we breathe out and plants breathe in--is the primary greenhouse gas (see definition) caused by the combustion of matter, including fossil fuels.

carbon neutral: Used to describe a person, company, or industry that accounts for its ecological footprint (see definition) by purchasing carbon offsets (see definition). This is the sort of adjective that pops up at benefit galas for chic environmental causes; think of "I'm carbon neutral" as the new "I'm a vegetarian." It's also a bit of a celebrity fad, and not just among the Clooney-DiCaprio set: British actress Sienna Miller, for example, professed to being carbon neutral in a February interview with fashion magazine Nylon.

carbon offsets: Carbon offsets are the best-known strategy for achieving the goal of carbon neutrality; in short, if you generate emissions somehow, you make up for it by investing in preventing or scrubbing out the same level of emissions. Some environmental bloggers frown on corporate carbon offsets as a cop-out that excuses companies from polluting as long as they plant a few trees here and there, but others argue it's a good start for companies that are investigating "green" policies but haven't yet reached the point where they can make bigger changes.

clean-burning: Not to be confused with "zero emissions." An adjective to describe an energy source that leaves minimal contamination--or at least less contamination than your average petroleum product. Natural gas, for example, is a clean-burning fuel.

Day After Tomorrow, The: Politically charged and somewhat poorly executed 2004 disaster movie, starring Randy Quaid and Jake Gyllenhaal, exposing the potentially apocalyptic effects of global warming, albeit in a scientifically implausible form. In green-tech slang, the title has become a synonym for "worst-case scenario." Notable for laughably ironic scene of hordes of illegal U.S. immigrants storming the border into Mexico to escape extreme weather in the north.

DiCaprio, Leonardo: Plenty of Hollywood types champion environmental causes, but the Prius-driving DiCaprio is arguably the most prominent of them all, a title that was reinforced by his appearance alongside Knut the baby polar bear on the cover of Vanity Fair magazine's 2007 "Green Issue." Ironically, his most famous film role remains the one in which his character experienced death by iceberg.

footprint: A clever metaphor for a person's, a company's, or an organization's overall environmental impact; "reducing one's footprint" is synonymous with changing lifestyle habits to use up fewer of the planet's resources. The easiest way to start? Switch those electricity-guzzling incandescent lightbulbs for compact fluorescent lights.

fossil fuels: The stuff we should probably stop using so much.

Gore, Al: Depending on your political leanings, he's either a visionary or an incredibly boring windbag, or maybe both. The consensus seems to be that he was right about the whole "climate change" thing, but that he could probably turn off a few of the lights in his house.

green: The ambiguity to end all ambiguities. Essentially, this just means "environmentally conscious" in whatever way you choose. Meanwhile, the gods of jealousy turn green with envy at the thought that they've lost their monopoly on the color.

greenhouse gas: A substance in the atmosphere (or which could potentially go into the atmosphere) that absorbs and re-emits infrared radiation, trapping heat close to Earth's surface and contributing to global warming. The most popular target is carbon dioxide, but others include methane, nitrous oxide, chlorofluorocarbons (CFCs), and water vapor. Yes, water vapor.

greenwashing: A pejorative, popular among eco-bloggers and pundits, targeted at corporations, government agencies, or other entities that are (allegedly) guilty of hypocritical environmental marketing or advertising. The "classic" example is of automotive companies that promote a hybrid (see definition) or a fuel-efficient vehicle as a flagship product while continuing to produce large, fuel-inefficient SUVs and trucks.

guerrilla: A much, much hipper and edgier version of "grassroots," complete with connotations of the underground and extralegal. Brought into the mainstream when a "guerrilla marketing" campaign for the Aqua Teen Hunger Force movie was mistaken for a terrorist plot. Oh, Boston.

Hummer: In eco-slang, this is a convenient shorthand for "the embodiment of everything wrong with the American automotive industry and culture surrounding it." This might change, however, as increasing numbers of Hummer owners retrofit their vehicles to burn biofuels.

hybrid: You probably already know this one--it refers to power that's derived from a combination of traditional (i.e. fossil-fuel burning) energy sources and more-efficient, lower-impact ones. Usually used in reference to cars, the most famous example being Toyota's Prius.

Knut: The way-too-adorable baby polar bear (just wait till he gets big) at the Berlin Zoo who has become the latest eco-celebrity--even sharing the Vanity Fair "Green Issue" cover with Leonardo DiCaprio. The Arctic habitats of polar bears, after all, are threatened by rising sea temperatures, and it always helps to have a cute face to represent a cause.

Kyoto: A truncation of "Kyoto Protocol," the international treaty introduced in 1997 (and famously snubbed by the United States) to assign limitations on greenhouse gas emissions in the hope of halting climate change. It expires in 2012, thus introducing "post-Kyoto" into forward-thinking environmental rhetoric as well.

No Impact Man: The superhero title given to Colin Beavan, the New York City writer who (along with his wife and kid) opted to spend an entire year generating absolutely no net impact on the environment. It might be tough, but it's scored him a New York Times article, a book deal, and an appearance on The Colbert Report. Sounds pretty good to us.

organic: 1) referring to chemical compounds with a carbon basis (i.e. organic chemistry); 2) referring to plants or animals that have been raised under specific conditions mandated by the U.S. Department of Agriculture (or equivalent government agency in other countries), without the use of pesticides, artificial hormones, radiation, and the like.

organic light-emitting diodes (OLEDs): Deserving of a mention here, if only to clear up any potential confusion involving the word "organic." OLEDs are made from carbon-based compounds rather than semiconductors, and are consequently believed to be more energy efficient (and can make even flatter TV screens). However, "organic" in this case does not refer to the "grown without pesticides" definition of the word.

Segway: Living proof that sometimes green tech is not particularly chic.

Schwarzenegger, Arnold: Hummer-driving action hero turned California governor, this is one guy whom the environmentalist community can't seem to make up its mind about. Yes, he's brought emissions-reducing policies to the forefront of political debate, but his lifelong penchant for big SUVs and disdain for "tree hugger" types has made him a controversial figure.

Soylent Green: 1) a post-apocalyptic environmental-catastrophe film that should probably be a few spots above The Day After Tomorrow in your Netflix queue; 2) people.

sustainable: This is another notoriously ambiguous one. Basically, it refers to resources that, if used wisely, can sustain life on earth indefinitely. You know, not oil.

zero emissions: Usually used in reference to transportation; a zero-emissions vehicle, or ZEV, produces absolutely no emissions--no soot, nitrogen oxides, hydrocarbons, what-have-you--when in use or idle. Examples include bicycles and solar-powered vehicles.

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