Illustrated Glossary of Organic Chemistry

Nor: A term included in the name of a molecule to indicate that the molecule has the same structure as its namesake, but minus a group (most frequently a methyl group). Nor is an abbreviation for 'normal'.


  

Epinephrine (adrenaline) has
a methyl group on the nitrogen atom.

Norepinephrine lacks the
methyl group on the nitrogen atom.