The Greek adjective adokimos (ἀδόκιμος) means disqualified, rejected, not approved, failing the test, or worthless. It is the alpha-privative form of dokimos (approved, tested, genuine). It appears seven times in the New Testament, used both of metals that fail the smelting test (Romans 1:28 — "a depraved/debased mind") and of Christian workers who might be "disqualified" from the prize (1 Corinthians 9:27; 2 Corinthians 13:5–7; 2 Timothy 3:8; Titus 1:16).
Paul's use of adokimos in 1 Corinthians 9:27 is one of the most sobering statements in all his letters: "I strike a blow to my body and make it my slave so that after I have preached to others, I myself will not be disqualified (adokimos) for the prize." Paul — apostle, church-planter, writer of half the New Testament — feared adokimos. This is not a statement about loss of salvation but about loss of the prize — the reward, the effectiveness, the finish. Paul compares himself to a boxer and a runner: discipline and self-control are not optional extras for the serious Christian; they are the training required to not be adokimos on the day of reckoning. The opposite of adokimos is dokimos — approved, tested, proven genuine. The Christian life is a race run toward dokimos, away from adokimos.