An Etymological Dictionary of Astronomy and Astrophysics

Occurring or coming after all others, as in time, order, or place. → last contact, → last quarter

Etymology (EN): Last, from O.E. latost (adj.) and lætest (adv.), superlative of læt (adj.) and late (adv.);
cognate with O.Fris. lest, Du. laatst, O.H.G. laggost, Ger. letzt.

Etymology (PE): Vâpasin, from vâ-, as intensive prefix, → de-,

• pasin, from pas “after, afterward, behind; finally, at last” (Mid.Pers. pas “behind, before, after;” O.Pers. pasā “after;” Av. pasca “behind (of space); then, afterward (of time);” cf. Skt. pazca “behind, after, later;”
  L. post “behind, in the rear; after, afterward;” O.C.S. po “behind, after;” Lith. pas “at, by;”
  PIE base *pos-, *posko-) + -in superlative suffix.