antifoulant; antifouling agent
Technical term used in marine, industrial, and coating contexts to refer to substances that prevent fouling (e.g., on ship hulls).
Antifouling agents are included in ship-bottom paint.
Compound of 防 (ぼう, 'prevent') + 汚 (お, 'dirt/fouling') + 剤 (ざい, 'agent'). A modern technical coinage.