society > occupation and work > equipment > machine > parts of machines > wheel > [noun] > cog or gear > with axis rotating around another > sun (2)
The central gear of an epicyclic or planetary gearing; = sun gear n. at sun, n.1 compounds 5a. Cf. sun-and-planet adj. at sun, n.1 compounds 5a.
the central gear of an epicyclic or planetary gearing, around which a planet gear revolves; = sun wheel, n. 2b; cf. sun-and-planet adj.