An Etymological Dictionary of Astronomy and Astrophysics

A movable barrier by which an entry is closed and opened.

Etymology (EN): M.E. dore, O.E. duru “door, dor gate;” akin to Ger. Tür, O.Norse dyrr, O.Irish dorus, Pers. dar, as below.

Etymology (PE): Dar “door,” Mid.Pers. dar; O.Pers. duvara-; Av. dvar-;
cf. Skt. dvár-; Gk. thura; L. fores;
Lith. dvaras “court-yard;” E. door, as above; PIE *dhwer-/*dhwor- “door, gate.”