Vain, empty, worthless, only found in Matt. 5:22. The Jews used it as a word of contempt. It is derived from a root meaning “to spit.”
Raca
1 verse
Matthew
Matthew 5:22
But I say unto you, That whosoever is angry with his brother without a cause shall be in danger of the judgment: and whosoever shall say to his brother, Raca, shall be in danger of the council: but whosoever shall say, Thou fool, shall be in danger of hell fire.
From Easton's Bible Dictionary
Matthew George Easton, 1897
From Smith's Bible Dictionary
William Smith, 1884
a term of reproach derived from the Chaldee reka , worthless. ("Raca denotes a certain looseness of life and manners, while “fool,” in the same passage, means a downright wicked and reprobate person.") (Matthew 5:22)