'alkali-vulnerable' is a compound formed from 'alkali' and 'vulnerable'. 'alkali' originates from Arabic, specifically the word 'al-qaly' (al-qaliy), where 'al-' was the Arabic definite article and 'qaly' referred to 'ashes (of saltwort)'; 'vulnerable' originates from Latin, specifically the word 'vulnerabilis', where 'vulner-' meant 'wound'.

'alkali' came into Medieval Latin and then into English via Old French/Medieval scholarly use from Arabic 'al-qaly' meaning ashes used to make soda; 'vulnerable' passed from Latin 'vulnerabilis' into Old French and Middle English and eventually into modern English. These two elements were later combined in English to form the descriptive compound 'alkali-vulnerable'.

Initially, 'alkali' referred specifically to plant ashes and alkaline salts used in early chemistry; over time it broadened to mean alkaline (basic) substances generally. 'Vulnerable' originally meant 'capable of being wounded' in a physical sense; it has since extended metaphorically to mean 'susceptible to harm or damage' in many contexts (physical, chemical, emotional, etc.).