Jealous God????

In the English translation of Bible,in Exodus,it said,I am a "jealous" God!
And in German translation ,it was "eifern",which means enthusiastic and agitate for sth .
I think this English word "Jealous "is not God's characteristic !

I used instinct to think ,who translate English Bible?
And I felt  the "Jealous God" ,was came from the famous poet --Milton ,although I didn't know him well,
but,maybe because he insult God,so did he blind!