An Etymological Dictionary of Astronomy and Astrophysics

1. Happening or arriving after an expected or arranged time; not on time, beyond usual time.
   

2. Belonging to an advanced stage or period in the development of something. → Late Heavy Bombardment, → late helium flash, → late thermal pulse, → late-type galaxy, → late-type star.

Etymology (EN): M.E., from O.E. læt “slow, late;” cf. Ger. lass “slothful;” O.N. latr, Goth. lats “slow, lazy;” L. lassus “tired, faint;” Gk. ledein “to be weary.”

Etymology (PE): Dir “late; tardily, slowly; a long while; old, antique,” from Mid.Pers. dêr, variants dagr, drâz “long”
(Mod.Pers. derâz “long,” variant Laki, Kurdi derež);
O.Pers. darga- “long;” Av. darəga-, darəγa- “long,” drājištəm “longest;” cf. Skt. dirghá- “long (in space and time);” L. longus “long;” Gk. dolikhos “elongated;” O.H.G., Ger. lang; Goth. laggs “long;” PIE base *dlonghos- “long.”
Dirân, adjective, variant of dir, as above.