The Collaborative International Dictionary of English v.0.48:

Piperidine \Pi*per"i*dine\, n. (Chem.)
   An oily liquid alkaloid, C5H11N, having a hot, peppery,
   ammoniacal odor. It is related to pyridine, and is obtained
   by the decomposition of piperine.
   [1913 Webster]