Is there any etymologyical connection between the mechanical noun, "gear", and "gyros" (Greek) / "gyre" (English) / "gyrus" (Latin)?

Because they both deal with round objects, and I'm not sure how gear went from "equipment" into "toothed spinning thing"...

"gyrus" comes from "gyros", and both mean 'circle', and are the origins of "gyre".

  • Please include the research you’ve done (and not just links). Questions that can be answered using commonly-available references are off-topic. – Edwin Ashworth Mar 3 '18 at 9:11

Their ultimate PIE origins appear to be different as shown below. The main sense of gear is that of “equipment and readiness” rather than a round object. “The mechanical sense of "toothed wheel in machinery" first attested 1520s; specific mechanical sense of "parts by which a motor communicates motion" is from 1814.


The etymological meaning of gear is roughly ‘that which puts one in a state of readiness’ – hence ‘equipment, apparatus’. Its ultimate source is prehistoric Indo-European garw-, which also produced the now obsolete English adjective yare ‘ready’ and (via Germanic, Italian, and French) garh (16th c.). A derivative *garwīn- passed into Old Norse as gervi, which English borrowed as gear. The mechanical sense of the word developed in the 16th century.



1560s, "a circular motion," from Latin gyrus "circle, circular course, round, ring," from Greek gyros "a circle, ring," related to gyrós "rounded," perhaps from PIE root geu- "to bend, curve".


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    I'm not sure that first source is reliable. The idea that "gear" is from some Indo-European source word like garw- doesn't look right. Germanic "g" usually comes from Proto-Indo-European voiced aspirated gh, whereas PIE "g" becomes Germanic "k". Wiktionary suggests that Proto-Germanic garwaz was derived in Germanic from ga- +‎ arwaz: en.wiktionary.org/wiki/Reconstruction:Proto-Germanic/garwaz – herisson Mar 3 '18 at 18:30
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    The NED (first OED) suggests PGer *garwe and the causative *garwjan, 'make ready,' which would get you the j-umlaut in ON. The perfective prefix makes a lot of sense. German gar doesn't have nearly the colorful history as this apparent cognate: Ist das Fleisch gar? just asks if the meat is ready/done. A gear in German is quite sensibly a Zahnrad, lit. 'toothwheel.' archive.org/stream/oed04arch#page/n731/mode/2up – KarlG Mar 3 '18 at 22:13

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