'phagocytosis-resistant' is a compound formed from 'phagocytosis' (from Greek roots) and 'resistant' (from Latin). 'Phagocytosis' comes from Greek 'phagein' meaning 'to eat' and 'kytos' meaning 'cell', combined with the suffix '-osis' indicating a process; 'resistant' derives from Latin 'resistere' meaning 'to stand back' or 'to withstand'.

'phagocytosis' was coined in the late 19th century (associated with Élie Metchnikoff/ Ilya Mechnikov) from Greek elements 'phagein' + 'kytos' + '-osis'; 'resistant' evolved from Latin 'resistere' → Old French/Medieval forms → Middle English 'resisten'/'resistant', producing the modern adjective 'resistant'. The compound form 'phagocytosis-resistant' is a modern English formation combining the scientific noun and the adjective.

Originally, 'phagocytosis' referred to the biological process 'cell eating' and 'resistant' meant 'able to withstand'; combined, the meaning developed as 'able to withstand being ingested by phagocytes', a specialized medical/biological sense.