Tunnelling

The fifth entry is o perno de ancoragem, the steel bar grouted into the rock above a heading, and English calls it « a rock bolt ». The noun looks dull and is the best travelled word on this page. In Old English a « bolt » was a short, thick arrow shot from a crossbow, and everything else grew out of that one object. A short thick rod of metal is a bolt, so the door has one and so does the nut. A creature that leaves like an arrow « bolts »: the horse bolted, the rabbit bolted, and a person can bolt for the door. Where the rabbit went is « a bolt-hole », which is now any place somebody keeps in order to disappear into it. Whoever sits stiff and straight sits « bolt upright », straight as the shaft. A man who has spent his last argument « has shot his bolt ». And the practical detail of anything whatever is « the nuts and bolts » of it. Portuguese divides all of this among o perno, o ferrolho, fugir and o esconderijo, and the arrow is visible in none of them.