'insect-free' is a compound formed from the words 'insect' and 'free'. 'Insect' originates from Latin, specifically the word 'insectum', where 'in-' meant 'into' and 'secare' meant 'to cut'. 'Free' originates from Old English 'frēo' (Proto-Germanic *frijaz) meaning 'not in bondage; beloved'.

'insect' came into English via Late Latin 'insectum' and Old French 'insecte' before appearing in Middle/Modern English as 'insect'. 'Free' developed from Old English 'frēo' through Middle English to modern 'free'. The compound 'insect-free' is a modern English formation combining these existing words.

Initially, 'insect' literally reflected the Latin sense related to 'cut into' but came to denote the class of small arthropods we call insects; 'free' originally meant 'not in bondage' and extended to mean 'without' or 'not affected by' in compounds like 'insect-free'.