'phylloxera-proof' is a modern English compound formed from 'phylloxera' and 'proof'. 'Phylloxera' entered English from New Latin 'Phylloxera' (the insect name), originally built from Greek elements 'phyllo-' meaning 'leaf' and a second element used in names for small pests; 'proof' comes from Old French 'prouve'/'prove', from Latin 'probare' meaning 'to test or demonstrate', later developing the sense 'resistant to' in compounds (e.g., 'bulletproof').

'phylloxera' was adopted into English botanical and entomological usage in the 19th century after the pest devastated European vineyards; 'proof' has been used as a combining suffix meaning 'resistant to' since the 19th century (as in 'bulletproof'), and the compound 'phylloxera-proof' arose in horticultural and viticultural contexts to describe rootstocks or treatments resistant to the pest.

Initially 'proof' mainly meant 'tested' or 'demonstrated'; over time in compounds it gained the extended meaning 'resistant to' or 'providing protection against', so 'phylloxera-proof' now means 'protected against phylloxera'.