I learned where the term Cis come from. Apparently the terms Cis and Trans are actually chemical terms used for the formations of fatty acids. I am sure you have heard of trans fats, these are formed by the Hydrogen bonds at the double carbon bond are on opposite sides of the hydrocarbon chain, causing the molecule to be straight. A Cis fat is when the Hydrogen atoms on the double carbon bond are on the same side of the Hrdrocarbon chain, causing the molecule to bend at an angle.