1. dikaios = just, righteous. From dike, right (see Ap. 177. 4).  Occ. eighty times; forty transl. "righteous"; thirty-three "just"; five times "right"; and thrice "meet".  In two places (Rom. 3:8.  Heb. 2:2) "just" is the rendering of endikos.  No other word in N.T. for "just", or "righteous".

2. dikaioo is to set forth as righteous, to justify.  Occ. forty times, of which fifteen are in Romans.  Always rendered "justify", except Rom. 6:7 ("freed"), and Rev. 22:11 ("be righteous").  The participle is transl. "justifier" in Rom. 3:26.

3. dikaiosune = righteousness.  Occ. ninety-two times, of which thirty-six are in Romans.  Always transl. "righteousness".  Other words to which the same transl. is given are dikaioma (see below), and euthutes, which latter occ. only in Heb. 1:8.

4. dikaioma is a righteous ordinance, a decree (of acquittal).  See Ap. 177. 4.  Rendered "righteousness" in Rom. 2:26; 5:18; 8:4.  Rev. 19:8; and "ordinance" in Luke 1:6.  Heb 9:1, 10 :  "judgment", Rom. 1:32. Rev. 15:4 :  "justification", Rom. 5:16.

5. dikaiosis = justification.  Occ. only in Rom. 4:25; 5:18.  The only other word rendered "justification" is dikaioma (see 4), in Rom. 5:16.