Englishfor English speakers
backsight
noun
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The rear sight of a firearm.
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(surveying) A measurement or reading taken back towards a point of known elevation, used to calculate the height of the surveying instrument (theodolite, transit, total station).
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(surveying) A measurement of a previously shot point, used to set the angle to zero when occupying a new position.
backsight
verb
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(surveying) To shoot a backsight.
hub
Noun
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A hub is the middle part of a wheel.
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A hub is a place where a large amount of traffic meets or passes through.
London's Heathrow Airport is a big air traffic hub in Europe.
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A hub is a simple networking device that sends all of the data (packets) that it gets to all of the other devices that are connected to it.
Mark bought a cheap hub to connect his home computers together.