An Etymological Dictionary of Astronomy and Astrophysics

Prefix denoting: “inside, within; below.” → intramolecular forces; → intermolecular forces;
→ intramercurian planet.

Etymology (EN): From L. intra “on the inside, within; during; below.” Commonly opposed to → extra-.

Etymology (PE): Darun “in, into; within” (Mid.Pers. andarôn
“inside,” from andar, → inter-, + rôn “side, direction;” Av. ravan- “(course of a) river”).
Dar “in, into; within,” from Mid.Pers. andar, → inter-.
Foru “down, downward; below; beneath” (Mid.Pers. frôt “down, downward;” O.Pers. fravata “forward, downward;” cf. Skt. pravát- “a sloping path, the slope of a mountain”).