Food science

El residuo de plaguicida tiene un límite máximo legal: the pesticide residue has a legal maximum. English has « residue » for exactly that, and then the Spanish word goes two places English will not follow. In arithmetic el residuo is what is left after a division — the remainder, and no English speaker calls that a residue. And in the plural it is rubbish: los residuos urbanos is municipal waste, la recogida de residuos the refuse collection, los residuos peligrosos hazardous waste. So the same noun covers the trace of poison in an apple, the four left over from thirteen, and the bins on the street — always what stays behind once the useful part has gone.