tro·choid /ˈtroˌkɔɪd, ˈtrɑˌkɔɪd/
 次擺線,軌跡線(a.)車輪狀的


 tro·choid /ˈtroˌkɔɪd/ 名詞
 車軸關節,擺動,次擺線,余擺線,圓錐形的,樞軸狀的


 Tro·choid, a.
 1. Anat. Admitting of rotation on an axis; -- sometimes applied to a pivot joint like that between the atlas and axis in the vertebral column.
 2. Zool. Top-shaped; having a flat base and conical spire; -- said of certain shells.
 3. Zool. Of or pertaining to the genus Trochus or family Trochidae.

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 Tro·choid n.  Geom. The curve described by any point in a wheel rolling on a line; a cycloid; a roulette; in general, the curve described by any point fixedly connected with a moving curve while the moving curve rolls without slipping on a second fixed curve, the curves all being in one plane. Cycloids, epicycloids, hypocycloids, cardioids, etc., are all trochoids.