An Etymological Dictionary of Astronomy and Astrophysics

Two graduated disks attached to the right ascension and declination axis of an equatorial mount used in amateur astronomy that help an observer find astronomical objects in the sky by their equatorial coordinates.

Etymology (EN): M.E.; O.E. settan “cause to sit, put in some place, fix firmly” (cf. O.N. setja, O.Fris. setta, Du. zetten, Ger. setzen); → circle.

Etymology (PE): Dâyeré, → circle; âmâj-giri “taking aim,” from âmâj “aim, target,” → point + giri “taking” (vebal noun of gereftan “to take, seize, hold;” Mid.Pers. griftan, gir- “to take, hold, restrain;” O.Pers./Av. grab- “to take, seize,”
cf. Skt. grah-, grabh- “to seize, take,” graha- “seizing, holding, perceiving,” M.L.G. grabben “to grab,” from P.Gmc. *grab, E. grab “to take or grasp suddenly;” PIE *ghrebh- “to seize”).