1. The chemical version of left-handed and right-handed.
2. While some molecules have the same atoms tied up in the same way, they are not physically the same because of their orientation.
3. The property possessed by an object; that is, a molecule, if it differs from its mirror image.

Such a chemical is called a chiral compound, and the two (or more) forms are called enantiomers (or optical isomers) of each other. Nearly all of the molecules that make up living systems are chiral.