Source : Webster's Revised Unabridged Dictionary (1913)

Sortition \Sor*ti"tion\, n. [L. sortitio, from sortiri to draw
   or cast lots, fr. sors, sortis, a lot.]
   Selection or appointment by lot. [Obs.] --Bp. Hall.

Source : WordNet®

sortition
     n : making a chance decision by using lots (straws or pebbles
         etc.) that are thrown or drawn [syn: {casting lots}, {drawing
         lots}]