Righteousness is the quality or state of being morally correct and justifiable. It can be considered synonymous with "rightness" or being "upright". It can be found in Indian religions and Abrahamic traditions, among other religions, as a theological concept. For example, from various perspectives in Hinduism, Buddhism, Islam, Christianity, and Judaism it is considered an attribute that implies that a person's actions are justified, and can have the connotation that the person has been "judged" or "reckoned" as leading a life that is pleasing to God.

William Tyndale (Bible translator into English in 1526) remodelled the word after an earlier word rihtwis, which would have yielded modern English *rightwise or *rightways. He used it to translate the Hebrew root צדק tzedek, which appears over five hundred times in the Hebrew Bible, and the Greek word δίκαιος (dikaios), which appears more than two hundred times in the New Testament.

Etymologically, it comes from Old English rihtwīs, from riht ‘right’ + wīs ‘manner, state, condition’ (as opposed to wrangwise, "wrongful"). The change in the ending in the 16th century was due to association with words such as bounteous.