'plague-preventive' originates from Modern English as a compound of 'plague' and 'preventive'. 'plague' comes (via Old French 'plague') from Late Latin 'plaga', where 'plaga' meant 'a blow, a stroke' and came to be used for severe pestilence; 'preventive' derives from Latin 'praeventivus' (from 'praevenire'), where the prefix 'prae-' meant 'before' and 'venire' meant 'to come'.

'plague' changed from Late Latin 'plaga' to Old French 'plague' and entered Middle English (forms such as 'plage'/'plague'), eventually becoming the Modern English word 'plague'. 'preventive' evolved from Latin 'praeventivus' through Medieval Latin and Middle French influences into the Modern English adjective 'preventive' (related to the verb 'prevent').

Initially, 'plague' originally referred to 'a blow' or 'stroke' and later came to denote a severe pestilence; 'preventive' originally carried the sense 'coming before' or 'taking precedence' and evolved to mean 'intended to prevent or protect against harm'. The compound 'plague-preventive' therefore now means 'intended to prevent pestilence'.