The Collaborative International Dictionary of English v.0.48:

Ibidem \I*bi"dem\, adv. [L.]
   In the same place; -- abbreviated ibid. or ib.
   [1913 Webster]

WordNet (r) 3.0 (2006):

ibidem
    adv 1: in the same place (used when citing a reference) [syn:
           ibid., ib., ibidem]

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

IBIDEM. This word is used in references, when it is intended to say that a
thing is to be found in the same place, or that the reference has for its
object the same thing, case, or other matter. IOU, contracts. The memorandum
IOU, (I owe you), given by merchants to each other, is a mere evidence of
the debt, and does not amount to a promissory note. Esp. Cas. N. A. 426; 4
Carr. & Payne, 324; 19 Eng. Com. L. Rep. 405; 1 Man. & Gran. 46; 39 E. C. L.
R. 346; 1 Campb. 499; 1 Esp. R. 426; 1 Man. Gr. & So. 543; Dowl. & R. N. P.
Cas. 8.