An Etymological Dictionary of Astronomy and Astrophysics

1. Being an original or primary source.
   
2. A basic principle, rule, law, or the like, that serves as the groundwork of a system.

Etymology (EN): L.L. fundamentalis “of the foundation,” from L. fundamentum “foundation,” from fundare “to found.”

Etymology (PE): Bonyâdin, adj. of bonyâd “foundation, basis,” from *bondâd (Mid.Pers. bune dâtak “foundation, basis”), from bon “basis; root; foundation; bottom” (Mid.Pers. bun “root; foundation; beginning,” Av. būna- “base, depth,” cf. Skt. bundha-, budhná- “base, bottom,” Pali bunda- “root of tree”)

• dâd “given,” from dâdan “to give” (Mid.Pers. dâdan “to give,” O.Pers./Av. dā- “to give, grant, yield,” dadāiti “he gives;” Skt. dadáti “he gives,” Gk. didomi “I give,” tithenai “to put, set, place;” L. dare “to give, offer;” Rus. delat “to do;” O.H.G. tuon, Ger. tun, O.E. don “to do”).