An Etymological Dictionary of Astronomy and Astrophysics

1. General: A closed, usually circular line that goes around an object or area.
   

2. Physics: → electric circuit.

Etymology (EN): From O.Fr. circuit, from L. circuitus “a going around,” from stem of circuire, circumire “go around,” from circum “around,” → circum- + -ire “to go” (cf. Gk. ienai “to go,” Skt. eti “goes,” O.Pers. aitiy “goes,” Av. aeiti “goes,” Mod.Pers. âyad “comes,” PIE *ei- “to go, to walk.”

Etymology (PE): Gardrâh, from gard “turning round, revolving,”
from gardidan “to turn, to change” (Mid.Pers. vartitan, Av. varət- “to turn, revolve,” Skt. vartati, L. vertere, O.H.G. werden “to become;” PIE *werto, *wer-)

• râh “way, path,” from Mid.Pers. râh, râs “way, street” (Mid.Pers. rah, ras “chariot”), from Proto-Iranian *rāθa-; cf. Av. raθa- “chariot;” Skt. rátha- “car, chariot,” rathyā- “road;” L. rota “wheel,” rotare “to revolve, roll;” Lith. ratas “wheel;” O.H.G. rad; Ger. Rad; Du. rad;
  O.Ir. roth; PIE *roto- “to run, to turn, to roll”).
  Barqrâh, from barq, → electricity, + râh, as above.