Abstract: Objective: To clarify the relations among the English words semantically associated with moon, including their etymologies, cultural implications and usages. Method: Adopting Indo -European philological study to investigate the related etymological issues, especially in sound change. Conclusion: Some related words are of IndoEuropean origin while others are otherwise derived; some related words function in word-formation while others do not. Significance: A systematic study of semantically related words concerning moon within the framework of IndoEuropean philology is new research, beneficial for both theoretical study and English lexical teaching practice.

Key words: moon, loan words, reflex, cognates, etymology, Indo-European philology