'algae-free' originates from the combination of 'algae' and 'free'. 'algae' originates from Latin, specifically the word 'alga', where it meant 'seaweed'. 'free' originates from Old English, specifically 'frēo', where it meant 'not enslaved' or 'exempt'.

'algae' was used in New Latin as 'alga' (plural 'algae') in scientific contexts and passed into English as 'algae'. 'free' changed from Old English 'frēo' to Middle English 'fre' and eventually to modern English 'free'; the compound 'algae-free' is a modern English formation combining the two elements.

Initially, 'alga' meant 'seaweed' and 'frēo' meant 'not enslaved'; over time the compound 'algae-free' evolved to mean 'without algae' or 'not affected by algae' in modern usage.