An Etymological Dictionary of Astronomy and Astrophysics

1. Having considerable linear extent in space. → very-long-baseline interferometry (VLBI).
   

2. Having considerable duration in time. → long-period variable.

Etymology (EN): M.E. longe, O.E. lang, long, akin to O.H.G., Ger. lang “long,” O.N. langr, M.Du. lanc, Goth. laggs “long,” L. longus, → longitude.

Etymology (PE): Derâz “long,” Mid.Pers. drâz “long;” O.Pers. darga- “long;” Av. darəga-, darəγa- “long,” drājištəm “longest;” cf. Skt. dirghá- “lon (in space and time).”