The Collaborative International Dictionary of English v.0.48:

Aliunde \A`li*un"de\, adv. & a. [L.] (Law)
   From another source; from elsewhere; as, a case proved
   aliunde; evidence aliunde.
   [1913 Webster]

Bouvier's Law Dictionary, Revised 6th Ed (1856):

ALIUNDE. From another place; evidence given aliunde, as, when a will
contains an ambiguity, in some cases, in order to ascertain the meaning of
the testator, evidence aliunde will be received.