sur·fac·tant
noun/sɜːˈfæktənt/
/sɜːrˈfæktənt/
[countable, uncountable]- (specialist) a substance that reduces the surface tension of a liquid, often forming bubbles in the liquid
表面活性剂（减少液体表面张力，常形成气泡） - (medical) a substance that keeps the lungs working well to prevent breathing problems
肺泡表面活性物质（维持肺部良好工作、防止呼吸困难）
Word Origin1950s: from surf(ace)-act(ive) + -ant.