Nephilim is a term used of the giants of the pre-flood generation who were apparently wicked (Gen. 6:5).  They were the offspring of the “sons of God” and women.  The term “sons of God” seems to indicate spiritual beings (Job 1:6; 2:1) in the Old Testament, but it is used by Christians in the New Testament (Luke 20:36; Rom. 8:14,19; Gal. 3:26).  The term “Nephilim” is used in Num. 13:33 in reference to people of huge size, which is probably a reference to their military strength.