'acid-neutralizing' is a modern English compound formed from 'acid' and 'neutralize'. 'acid' originates from Latin, specifically the word 'acidus' meaning 'sour' or 'sharp', and 'neutralize' ultimately comes via French 'neutraliser' from Medieval Latin 'neutralis' (from Latin 'neuter') meaning 'neither of two'.

'acid' comes from Latin 'acidus' and entered English via Old French/Latin routes; 'neutralize' appeared in scientific English in the 18th–19th centuries from French 'neutraliser' (itself from 'neutral' + French verbal suffix) and was later combined with 'acid' to form the compound adjective 'acid-neutralizing' in modern technical use.

Initially 'acid' simply meant 'sour' and 'neutralize' meant 'make neutral'; over time the compound came to be used specifically in chemistry and medicine to mean 'capable of counteracting acidity'.