An Etymological Dictionary of Astronomy and Astrophysics

The time interval between two successive passages of the Moon through its → ascending node, 27.212 220 days (27d 5h 5 m 35.8s). Draconic month is important for predicting → eclipses.
Also called draconitic month, nodical month.

Etymology (EN): Draconic, adj. of dragon, → Draco, referring to a mythological dragon for the following reason. Since an eclipse occurs when the Earth, the Sun, and a node are aligned and moreover the Moon is situated near the node, it was believed that a dragon that resided in the node swallowed the Sun or the Moon. → month.

Etymology (PE): Mâh, → month.
Gowzahri, related to gowzahr, from Mid.Pers. gowzihr “a node of the lunar orbit” [gowzihr sar (“head”) = ascending node, gowzihr dumb (“tail”) = descending node], also the astrological dragon, from Av. gao-ciθra- “keeping in it the seed of the ox,” epithet of the Moon, since according to Iranian mythology the Moon keeps the seed/sperm of bovine animals; from gao- “cow, ox, bull” (Mod.Pers. gâv, Skt. gaus-, Gk. bous “ox,”
Arm. kov, O.E. cu, PIE *gwou-)

• ciθra- “origin, seed, lineage” (Mod.Pers. cehr “origin”). Gowzahr was loaned into Arabic astronomical texts as jawzahr.
  Gerehi, adj. of gereh→ node.