'tumor-inhibiting' is a compound formed from 'tumor' and 'inhibiting'. 'tumor' originates from Latin, specifically the word 'tumor', where the root meant 'swelling'. 'inhibit' originates from Latin, specifically the word 'inhibere', where the prefix 'in-' meant 'in' (or 'into') and the root 'habere' meant 'to hold'.

'tumor' changed from Latin word 'tumor' into Medieval/Old French and Middle English forms like 'tumour' and eventually became the modern English word 'tumor'. 'inhibit' came from Latin 'inhibere' and passed into Late Latin/Medieval Latin and Middle English before becoming the modern English 'inhibit' (with the present participle 'inhibiting'). The compound 'tumor-inhibiting' is a modern English formation combining these elements.

Initially, 'tumor' meant 'swelling' in Latin and 'inhibere' meant 'to hold in' or 'restrain'; over time these elements combined in modern English to form 'tumor-inhibiting', which now specifically means 'preventing or reducing tumor growth'.