Energy law and the grid

The fourteenth entry is o mercado diário, and the adjective inside it is the most expensive word on this page for anybody writing in English. Diário is « daily », and nothing in the Portuguese is misleading: the market does sit every day. But the settled English name is the « day-ahead market », and it is settled because English named the thing by what is being traded rather than by how often the trading happens. What changes hands on o mercado diário is electricity for tomorrow, hour by hour, and the closing time in the example — midday on the day before — is the whole of the point. Write « daily market » and an English reader hears a market that opens every morning, which says nothing at all, since every market named on this page does. The trap is worth noticing because the entry directly after it does not spring it: o mercado intradiário is the « intraday market », and there the prefix and the base both carry across untouched. One of the pair behaves, the other does not, and only the second has a name of its own in English.