Castaway

kast'-a-wa (adokimos, from dokimazo, "I test," "I approve after testing," hence, approved after being tested): This word is rendered "castaway" only in the King James Version: "I myself should be a castaway" ("rejected" the Revised Version (British and American), the American Standard Revised Version, 1Co 9:27). But the same word occurs a number of times usually translated "reprobate" (Ro 1:28; 2Co 13:5-7; 2Ti 3:8; Tit 1:16); "rejected" (Heb 6:8).

⇒See the definition of castaway in the KJV Dictionary

⇒See also the McClintock and Strong Biblical Cyclopedia.