Illustrated Glossary of Organic Chemistry

Geometric isomer: One molecule in a set of stereoisomers which differ in the E/Z or cis/trans arrangement of substituents or functional groups.

E and Z Geometric Isomers

E-2-Butene  
Z-2-Butene

Cis and trans Geometric Isomers

Cis-1,2-Dimethylcyclobutane   
Trans-1,2-Dimethylcyclobutane