The Collaborative International Dictionary of English v.0.48:

Udal \U"dal\ ([=u]"dal), n. & a. Udalborn \U"dal*born`\, Udaler
\U"dal*er\, Udalman \U"dal*man\, etc.[Icel. [=o][eth]al
   allodium, an hereditary estate; akin to Sw. odal allodial,
   Dan. odel.]
   Vars. of Odal, etc.; property held by udal, or allodial,
   right -- Obs. exc. in Shetland and the Orkney Islands, where
   udal designates a freehold, land held in fee simple without
   any charter and free of any feudal character.
   [Webster 1913 Suppl.]

The Collaborative International Dictionary of English v.0.48:

Udaler \U"dal*er\, Udalman \U"dal*man\, n.
   In the Shetland and Orkney Islands, one who holds property by
   udal, or allodial, right. --Sir W. Scott.
   [1913 Webster]