A neuter noun designating success, right achievement, or virtuous action—something accomplished correctly. Classical philosophers distinguish it from mere good fortune (εὐτύχημα): a κατόρθωμα results from virtue and skill, not luck. In Stoic ethics, these are 'perfect actions' fulfilling all duties, opposed to sins (ἁμαρτήματα). Literary critics use it for stylistic excellence. The word implies not just success but rightness—moral quality in achievement. The New Testament employs it (in variant readings) for righteous deeds accomplished through faith. Root meaning: that which is set upright, made straight, perfected.