Gibborim (גּבּר ,גּבּור) is a Hebrew word that can be glossed "mightiest" which is an intensive for gabar (גּבר) that can be glossed "mighty". Many times it is used of people who are valiant, mighty, or of great stature. There is some confusion between Gibborim as a class of beings because of its use in Genesis 6:4. However, this passage describes the Nephilim as mighty (gibborim).
The word gibborim is used in the Tanakh in excess of 150 times and applied to men as well as lions (Book of Proverbs 30:30), hunters (Genesis 10:9), soldiers (Book of Jeremiah 51:30) and leaders (Book of Daniel 11:3).
In modern Hebrew the word "gibbor" (the singular form of 'gibborim'), equates with 'hero' (if noun), or 'brave' (if adjective).