'alkaline-tolerant' is formed from 'alkaline' (from Arabic 'al-qaly', meaning 'ashes of saltwort') and 'tolerant' (from Latin 'tolerare', meaning 'to endure').

'alkaline' entered English via Medieval Latin 'alkalina', and 'tolerant' from Old French 'tolerant', both eventually combining in modern English as 'alkaline-tolerant'.

Initially, 'alkaline' referred to substances with basic properties, and 'tolerant' meant able to endure. Combined, the term now means able to endure alkaline conditions.