Source : Webster's Revised Unabridged Dictionary (1913)

Endanger \En*dan"ger\, v. t. [imp. & p. p. {Endangered}; p. pr.
   & vb. n. {Endangering}.]
   1. To put to hazard; to bring into danger or peril; to expose
      to loss or injury; as, to endanger life or peace.

            All the other difficulties of his reign only
            exercised without endangering him.    --Burke.

   2. To incur the hazard of; to risk. [Obs.]

            He that turneth the humors back . . . endangereth
            malign ulcers.                        --Bacon.

Source : WordNet®

endanger
     v 1: pose a threat to; present a danger to; "The pollution is
          endangering the crops" [syn: {jeopardize}, {jeopardise},
           {menace}, {threaten}, {imperil}, {peril}]
     2: put in a dangerous, disadvantageous, or difficult position
        [syn: {queer}, {expose}, {scupper}, {peril}]