Illustrated Glossary of Organic Chemistry

Polycyclic aromatic hydrocarbon (PAH): An aromatic hydrocarbon whose molecular structure contains two or more fused benzene rings. Some representative examples are shown below.






Naphthalene
A bicyclic PAH
  
Anthracene
A tricyclic PAH
  
Phenanthrene
A tricyclic PAH






Benzo[a]pyrene
  
Coronene
  
Graphene




Triphenylmethane   
Fluorene
Triphenylmethane and fluorene are both hydrocarbons with two or more benzene rings, but neither are classified as polycyclic aromatic hydrocarbons because they both lack fused benzene rings.