'vesicle-free' is a compound of 'vesicle' and 'free'. 'vesicle' originates from Latin, specifically the word 'vesicula' where 'vesica' meant 'bladder', and 'free' originates from Old English 'frēo' meaning 'not in bondage or exempt'.

'vesicle' entered English via Medieval Latin 'vesicula' and eventually became modern English 'vesicle'; 'free' developed from Old English 'frēo' through Middle English to the modern adjective 'free'.

Initially, 'vesicula' meant 'small bladder' in Latin and 'free' meant 'not in bondage'; over time 'vesicle' came to mean a small sac or membrane-bound compartment in biology, and 'free' retained and generalized its sense of 'not containing or not having', yielding the compound meaning 'not containing vesicles'.