The practice of leaving one's country or army.
Key passages
Je 37:13–14

And when he was at the Gate of Benjamin, there was a sentry on duty whose name was Irijah, the son of Shelemiah, the son of Hananiah, and he seized Jeremiah the prophet, saying, “You are deserting to the Chaldeans!” And Jeremiah said, “That is a lie! I am not deserting to the Chaldeans.” …

1 Mac 7:19

And Bacchides departed from Jerusalem and camped at Bethzaith and sent and seized many from those with him, men who had deserted, and some of the people and slaughtered them in a great pit.

1 Mac 7:23–24

And Judas saw all the evil that Alcimus and those with him had done among the children of Israel. It was beyond what the nations had done. And he went out in all the borders of Judah, and all around, and executed vengeance on the men who had deserted, and they were prevented from going into …

1 Mac 9:6–7

And they saw the great number of the army, that they were many, and they became very afraid, and many slipped away from the army; only eight hundred of them remained. And Judas saw that his army had slipped away and the battle was imminent upon him, and he was crushed in his heart because he …

3 Mac 2:33

And they had restored good hope for obtaining help, and those departing from them, they were abhorring, and they were judging them as enemies of the people, and they were depriving them of communal association and help.