Select the most appropriate one-word substitution for the given group of words.

A scientific study insects 

Entomology 

The most appropriate one-word substitution for "a scientific study of insects" is entomology.

• Entomology is the scientific study of insects.
• Etymology is the study of the history of words and their origins.
• Cardiology is the study of the heart and its functions.
• Palaeology is the study of ancient life and cultures.