'countercathartic' is formed from the prefix 'counter-' meaning 'against' and the word 'cathartic' meaning 'purging' or 'cleansing' (see 'cathartic').

'counter-' originates from Old French 'contre' (from Latin 'contra') meaning 'against'; 'cathartic' ultimately comes from Greek 'kathartikos' (from 'kathairein' meaning 'to cleanse'), passed into Latin and then Middle English as 'cathartic' before being combined with 'counter-' to form the modern compound 'countercathartic'.

Initially, the roots conveyed the sense of 'against cleansing' in a literal compositional way; over time the compound has been used specifically to denote agents or qualities that oppose either medicinal purging or emotional catharsis.