The Collaborative International Dictionary of English v.0.48:

Battle-ax \Bat"tle-ax`\ Battle-axe \Bat"tle-axe`\(-[a^]ks`), n.
   (Mil.)
   A kind of broadax formerly used as an offensive weapon.
   [1913 Webster]

WordNet (r) 3.0 (2006):

battle-axe
    n 1: a sharp-tongued domineering wife [syn: battle-ax,
         battle-axe]
    2: a broadax used as a weapon [syn: battle-ax, battle-axe]

Easton's 1897 Bible Dictionary:

Battle-axe
   a mallet or heavy war-club. Applied metaphorically (Jer. 51:20)
   to Cyrus, God's instrument in destroying Babylon.