It took 10 years, but Merriam-Webster has finally recognized "dark energy," adding the term—used to describe the perplexing force that is causing galaxies to accelerate away from one another—to some 100 other new dictionary entries this year. Some hesitation was appropriate: As with any new discovery, researchers needed time to digest and confirm the 1998 finding of dark energy, made by analyzing the light coming from distant supernovae. The origin of dark energy is one of the biggest mysteries in physics, but its existence is now well accepted. Researchers believe it will eventually leave individual galaxies isolated in vast oceans of empty space. Among this year's other geeky dictionary-worthy words: dwarf planet (Pluto and other smallish round bodies in the solar system, recently rechristened "plutoids"); malware (harmful computer software); norovirus; phytonutrient; and air quotes, the gesture you no doubt made if you read this out loud.