'phagocytosis' originates from New (Modern) Latin/Neo-Latin, ultimately built from Ancient Greek 'phagein' and 'kytos', where 'phagein' meant 'to eat' and 'kytos' meant 'container' or 'cell'.

'phagocytosis' was coined in scientific usage in the late 19th century (credited to Ilya Mechnikov and other immunologists) in New Latin and was adopted into English largely unchanged from the scientific Latin coinage.

Initially it literally meant 'cell eating' (the act of a cell consuming material); over time this literal image has persisted but the term has been specialized to refer to the specific cellular mechanisms and immunological role of that process.