'anticholinesterase' is formed from the prefix 'anti-' (meaning 'against') + 'cholinesterase' (the enzyme name). 'anti-' originates from Greek 'anti' meaning 'against' and was adopted into English as a productive prefix.

'cholinesterase' itself is built from 'choline' (from Greek 'chole' for 'bile' → the chemical name 'choline') + 'esterase' (ester + '-ase', the enzyme suffix). The compound word 'anticholinesterase' arose in 20th-century biochemical/medical usage by prefixing 'anti-' to the enzyme name to denote inhibitors.

Initially the components meant 'against' + the enzyme name; the combined word has consistently meant 'an agent that opposes or inhibits cholinesterase,' and this technical sense has remained stable in biochemical and medical contexts.