The Collaborative International Dictionary of English v.0.48:

jeopardize \jeop"ard*ize\, v. t. [imp. & p. p. Jeopardized; p.
   pr. & vb. n. Jeopardizing.]
   To expose to loss or injury; to risk.

   Syn: jeopard.
        [1913 Webster]

              That he should jeopardize his willful head
              Only for spite at me.               --H. Taylor.
        [1913 Webster]

WordNet (r) 3.0 (2006):

jeopardize
    v 1: pose a threat to; present a danger to; "The pollution is
         endangering the crops" [syn: endanger, jeopardize,
         jeopardise, menace, threaten, imperil, peril]
    2: put at risk; "I will stake my good reputation for this" [syn:
       venture, hazard, adventure, stake, jeopardize]

Moby Thesaurus II by Grady Ward, 1.0:

19 Moby Thesaurus words for "jeopardize":
   compromise, encounter danger, endanger, expose, gamble,
   gamble with, hazard, imperil, incur danger, jeopard, jeopardy,
   lay open, menace, peril, put in danger, put in jeopardy, risk,
   threaten, venture