'cytolysin' originates from Greek (via New Latin), specifically from the Greek roots 'kytos' and 'lysis', where 'kytos' meant 'cell/container' and 'lysis' meant 'loosening, dissolution'.

'cytolysin' was formed in scientific New Latin by combining the combining form 'cyto-' (from Greek 'kytos') with the suffix '-lysin' (from Greek 'lysis'), and entered modern English usage in late 19th to early 20th century biology and microbiology literature to denote agents that lyse cells.

Initially it referred specifically to an agent causing lysis of cells; over time the term has retained that core sense while broadening to cover a range of cell-destroying toxins and factors from diverse organisms and immune responses.