Wolf, C. Dynamic Stereochemistry of Chiral Compounds:Principles and Applications 2008! Nomenclature for assigning atropisomers! 3 Bringmann, G.; Mortimer, P. A. J.; Keller, P. A.; Gresser, M. J.; Garner, J.; Breuning, M. Angew.
Cis–trans isomerism, also known as geometric isomerism or configurational isomerism, is a term used in organic chemistry. The prefixes "cis" and "trans" are from Latin: "this side of" and "the other side of", respectively.
In chemistry, conformational isomerism is a form of stereoisomerism in which the isomers can be interconverted just by rotations about formally single bonds (refer to figure on single bond rotation).
Stereochemistry, a subdiscipline of chemistry, involves the study of the relative spatial arrangement of atoms that form the structure of molecules and their manipulation. The study of stereochemistry focuses on stereoisomers, which by definition have the same molecular formula and sequence of bonded atoms (constitution), but differ in the three-dimensional orientations of their atoms in space.
Stereochemistry is the 3D conformation of molecules. It doesn't have to do with what atoms are present, or even in what order they are connected, it has to do with what direction each of those connections are pointing.