From a (as a negative particle) and dokimos; unapproved, i.e. Rejected; by implication, worthless (literally or morally) -- castaway, rejected, reprobate.
KJV: And even as they did not like to retain God in their knowledge, God gave them over to a reprobate mind, to do those things which are not convenient;
NASB: And just as they did not see fit to acknowledge God any longer, God gave them over to a depraved mind, to do those things which are not proper,
KJV: Examine yourselves, whether ye be in the faith; prove your own selves. Know ye not your own selves, how that Jesus Christ is in you, except ye be reprobates?
NASB: Test yourselves to see if you are in the faith; examine yourselves! Or do you not recognize this about yourselves, that Jesus Christ is in you-- unless indeed you fail the test?