 Today in surprisingly connected etymologies, we're going on strike. Being on strike can produce a certain amount of stress and strain. But even though this goes along with the etymological territory, ultimately it should have a very different effect. Strike used to have an almost opposite sense, to touch softly rub, and is related to stroke, with strike, stroke, strain, and stress all going back to the Proto-Indo-European root straig, to stroke, rub, press. The more violent sense of hit hard didn't appear until the 13th century, and the labour disruption sense developed in the 18th century from the notion of downing one's tools, particularly sailors striking the sails when they didn't want to leave port. What does picketing have to do with magpies? A lot it turns out. Picket in the sense of picket lines comes originally from a military formation in which soldiers were stationed with pikes, a related word. Picket comes into English from French piquet, from Latin piquus woodpecker, and pica magpie, ultimately from the Proto-Indo-European root spake, which referred to the birds as well. The pie in magpie also comes from this root, and when a person is referred to as a magpie, it means they're a hoarder of things or information, or that they're a chatterer. Why do universities need unions? Etymology. It's probably clear that both words come from Latin unus one. A union is a collection of workers. You might have thought that the word university reflects the idea of universal education or the universal coverage of subjects, but in fact it's short for Universitas Magistrom at Scholarium, the union of teachers and students. The university started out as a kind of scholastic guild to protect their interests against outside non-academic forces, reducing the financial barriers to education and protecting the livelihood of the teachers. What is a labour union to do when their contract has lapsed? Turn to etymology. Labour comes from Latin labour, toil, distress, trouble. Its deeper etymology is uncertain, but one suggestion is that it's related to labare, to totter and or labi, to slip, which also gives us the word lapse. And if so, this would mean the underlying sense of labour is to stumble under a burden, but one thing a labour union won't do is collapse, literally to fall together. And finally, solidarity will save the day. Solidarity and solid come from Latin solidus, solid whole, which can be traced back to the proto-Indo-European root sol, whole. This also leads to the Latin word salvus, safe, healthy, which having passed through old French ultimately gives us the words safe and save. Thanks for watching. This is one in a series of occasional short videos about connected etymologies. To see more, you can also follow the endless knot on Twitter, Facebook or Instagram.