Raca is a word that comes from the Aramaic term reqa. It was a derogatory expression meaning empty-headed.
1 If you called someone Raca you were insinuating that they are stupid and inferior to you. As such, it is an offensive name used to show contempt for another person.
22 But I say to you that everyone who is angry with his brotherwill be liable to judgment; whoever insultshis brother will be liable to the council; and whoever says, ‘You fool!’ will be liable to the hellof fire.