Sentence:  With <WSD>boomerang</WSD> and spear they hunted the kangaroo and emu, and fought their battles beneath the eucalyptus forests; their minds, fresh, untroubled, contented, oblivious alike of noble ideals and philosophic principles. 
Meaning of the word marked with <WSD> tags:  A flat curved airfoil, that spins about an axis perpendicular to the direction of flight, that was originally used in various parts of the world as hunting weapons or, in returnable types, for sports or training.