The Collaborative International Dictionary of English v.0.48:

Tuberculin \Tu*ber"cu*lin\, n. [See Tubercle.]
   A fluid containing the products formed by the growth of the
   tubercle bacillus in a suitable culture medium.
   [1913 Webster]

WordNet (r) 3.0 (2006):

tuberculin
    n 1: a sterile liquid containing a purified protein derivative
         of the tuberculosis bacterium; used in the diagnosis of
         tuberculosis