The word "arms" in the title of the book could be explained in a couple of different ways. First, the text does take place during World War I, with Frederic Henry, the protagonist, serving as a soldier, and Catherine Barkley, his love interest, serving as a nurse, so "arms" can refer to the weapons used in such a war. The couple does say farewell to arms, in terms of weapons, when they escape to Switzerland. Further, "arms" could refer to the arms of a lover, especially considering Catherine's death after giving birth to her stillborn son, a death which leaves Frederic alone. He literally must say farewell to her loving arms. Finally, the entire title itself could allude to a poem written by George Peele in the late sixteenth century. In this poem, the speaker laments that he will no longer be able to serve Queen Elizabeth in battle because he has grown old; he must give up the armaments of war.