Cosmetic chemistry

The ninth entry is o tensioativo, and the English word for it is the odd one out on this page, because it is not a translation of anything: it is a contraction. Portuguese built its term the transparent way, out of tensão and ativo, so a reader who knows what surface tension is can take the noun apart and see the job it names. English had exactly the same phrase available, « surface-active agent », and instead of keeping it the trade squeezed the three words into one: « surf » from the first, « act » from the second, « ant » from the tail of the third. Nothing in the result can be taken apart again. It has to be learned whole, and a reader who meets it on the back of a shampoo bottle has no way in at all. That is what makes it worth a stop rather than a line in a glossary: the neighbouring terms on this list stayed readable — « an emulsifier » emulsifies, « a thickener » thickens, « a preservative » preserves — and « surfactant » alone has its own definition folded up inside it.