Machining

The eighteenth entry is a trepidação, and an English reader who recognises the word has already understood the wrong thing. « Trepidation » in English is a state of mind, the unease somebody carries into a difficult meeting, and it is said of people and of nothing else: « she opened the letter with some trepidation ». A trepidação describes no feeling whatever. It is physical shaking — the tremor a lorry sends through a floor, and at the lathe the self-sustaining vibration between tool and workpiece that prints a row of waves down the wall of the cut. The Latin verb behind both words is trepidare, to tremble in alarm, and each language kept one half of it: English took the alarm and let the trembling go, Portuguese took the trembling and left the alarm to o receio. The trade word English reaches for instead is « chatter », which names the same defect by its noise rather than by its motion. So a máquina trepida is a machine shaking itself towards a scrapped part, never a machine having second thoughts.