This is a transliterated Aramaic insult meaning 'empty,' 'worthless,' or 'empty-headed,' preserved in Jesus' teaching about anger in the Sermon on the Mount. Rather than translating it, most versions simply transliterate it as 'Raca' or similar phonetic forms, recognizing it as a contemptuous term of address that degrades another person's worth or intelligence. Jesus uses this term to warn that contemptuous anger carries severe moral weight, even when it doesn't escalate to physical violence. The word derives from Hebrew רֵיק (rēq), meaning 'empty' or 'vain.'