'alkali-intolerant' is a modern English compound formed from 'alkali' + 'intolerant'. 'alkali' originates from Arabic, specifically the word 'al-qaly', where 'al-' meant 'the' and 'qaly' meant 'ashes of saltwort' (used historically in soapmaking). 'intolerant' originates from Latin, specifically the word 'intolerans', where the prefix 'in-' meant 'not' and 'tolerans' meant 'able to bear.'

'alkali' passed into Medieval Latin and later into European languages from Arabic 'al-qaly', then into English as 'alkali' with its meaning shifting toward substances that are basic/alkaline; 'intolerant' came from Latin 'intolerans' through Old French/Middle English to modern English 'intolerant'. The compound 'alkali-intolerant' was formed in modern English by joining these two elements to describe inability to tolerate alkaline conditions.

Initially, 'alkali' referred to ashes used in traditional soapmaking and alkali-related materials, while 'intolerant' simply meant 'unable to bear'. Over time 'alkali' acquired the modern chemical sense of 'basic/alkaline', and the compound 'alkali-intolerant' now specifically denotes inability to tolerate alkaline (high-pH) substances or environments.