one of the three districts into which Yorkshire was divided, 1295, from late O.E.
*þriðing, a relic of Viking rule, from O.N.
ðriðjungr "third part," from
ðriði "third" (see
third). The initial consonant merged with final consonant of preceding
north, west, or
east.
[rahy-ding] 
dɪŋ