'pellagra-preventive' is a compound of 'pellagra' and 'preventive'. 'pellagra' originates from Italian, specifically the phrase 'pelle agra', where 'pelle' meant 'skin' and 'agra' meant 'sour' or 'rough'. 'preventive' originates from Latin, specifically the word 'praeventivus', where 'prae-' meant 'before' and 'venire' (via Latin/French forms) meant 'to come'.

'pellagra' entered English from Italian 'pelle agra' in the 18th century as the name of the disease; 'preventive' came into English via Old French/Medieval Latin from Latin 'praeventivus'. The compound 'pellagra-preventive' is a modern English formation combining these established elements.

Initially, 'pellagra' literally meant 'sour skin' referring to the skin symptoms of the disease; over time it became the medical name for the niacin-deficiency disease. 'Preventive' initially meant 'coming before' or 'forestalling' and evolved to mean 'intended to prevent' in medical and general use; together the compound now means 'intended to prevent pellagra'.