Illustrated Glossary of Organic Chemistry

Paraffin: (1) An old term for a saturated acyclic alkane (not a cycloalkane). Now mostly out of use.



Methane
   
Hexane
   
2-Methylpentane
Methane, hexane, and 2-methylpentane are all paraffins (saturated alkanes).




Ethylene
   
Cyclohexane
Ethylene is an alkene. Cyclohexane is a cycloalkane. Neither of these molecules are paraffins.

(2) A wax composed mostly high molecular weight hydrocarbons, having typically twenty to forty carbon atoms per molecule. Parafilm is a thin, flexible, stretchable paraffin wax film, often used in the laboratory to seal containers.

Blocks of paraffin wax.
   
Canned peaches.


Paraffin wax is used for home canning, and is often available in grocery stores.   
A bottle of iodine sealed with Parafilm.