Berean Standard Bible, Matthew 5:
BDGA:
Strong's Greek: 4469. ῥακά (rhaka) — 1 OccurrenceI tell you that anyone who is angry with his brother will be subject to judgment. Again, anyone who says to his brother, ‘Raca,’ will be subject to the Sanhedrin. But anyone who says, ‘You fool!’ will be subject to the fire of hell.
BDGA:
Expositor's Greek Testament:a term of abuse/put-down relating to lack of intelligence, numskull, fool … empty-head. … [It] is not an expression denoting a strong put-down. .. It is a colloquial term of rather gentle cheek and generally used in familiar surroundings.
"Raca" was a mild insult. Jesus warned us against insulting our brothers in the Sermon on the Mount.Raca expresses contempt for a man’s head = you stupid!