Aviation and flight operations

The fortieth entry is a corrente de jato, the ribbon of fast air that shortens a flight eastwards, and the English name for it, « the jet stream », holds a word that is really two, wearing one spelling. The « jet » of « jet stream », of « jet engine » and of « a jet of water » came in from French jet, from jeter, and behind that stands Latin iactare, to throw. A jet, on that side of the family, is something thrown out. The « jet » of « jet-black » has nothing to do with throwing. It is a hard black lignite that takes a polish and was cut into mourning jewellery, and its name reached English through Latin gagates, from Greek, the stone of Gagai in Lycia. Two ancestries, one syllable, and English leaves no mark on the seam, so « jet-black hair » and « a jet of steam » look like one word doing two jobs and are not. Portuguese never had to sort this out. O jato is the thrown thing, and the black stone is o azeviche, a word that arrived through Arabic and shares nothing with it.