Source : Webster's Revised Unabridged Dictionary (1913)

Yon \Yon\ (y[o^]n), a. [OE. yon, [yogh]on, AS. geon; akin to G.
   jener, OHG. jen[=e]r, Icel. enn, inn; cf. Goth. jains.
   [root]188. Cf. {Beyond}, {Yond}, {Yonder}.]
   At a distance, but within view; yonder. [Poetic]

         Read thy lot in yon celestial sign.      --Milton.

         Though fast yon shower be fleeting.      --Keble.

Yon \Yon\, adv.
   Yonder. [Obs. or Poetic]

         But, first and chiefest, with thee bring Him that yon
         soars on golden wing.                    --Milton.

Source : WordNet®

yon
     adv : at or in an indicated (usually distant) place (`yon' is
           archaic and dialectal); "the house yonder"; "scattered
           here and yon"- Calder Willingham [syn: {yonder}]

yon
     adj : distant but within sight (`yon' is dialectal); "yonder
           valley"; "the hills yonder"; "what is yon place?" [syn:
            {yonder}]