A 3D-generated image of the coronavirus variant of concern known as omicron. The little bumps are spike proteins (see definition below). Uma Shankar Sharma/Getty Images hide caption toggle caption Uma Shankar Sharma/Getty Images Goats and Soda Coronavirus FAQ: Help me with omicron vocab. What's immune evasion? Epistasis? December 3, 2021 The emergence of this new variant of concern has brought a new vocabulary into daily news reports. We asked experts to help define the terms you're being bombarded with.