'antihaemolysin' originates from Greek elements: the prefix 'anti-' meaning 'against' and 'haemolysin' from Greek 'haima' meaning 'blood' plus 'lysis' meaning 'loosening' or 'dissolution'.

'haemolysin' was formed from Greek 'haima' + 'lysis' and entered scientific/medical Latin and English as 'haemolysin' (also spelled 'hemolysin' in US English); adding the prefix 'anti-' produced 'antihaemolysin' to denote an agent acting against haemolysin.

Initially coined to denote a substance acting against blood-destroying agents (literally 'against haemolysin'); this core meaning — an agent that neutralizes or inhibits haemolysin — has been retained in modern usage.