The phrase “straight and narrow” refers to a path of moral integrity, righteousness, or discipline. It originates from a biblical passage in Matthew 7:14, which describes the way to salvation as a “narrow” path that few people find. Over time, the expression has come to mean adhering to strict moral or ethical principles and avoiding temptation or wrongdoing.
For example, someone who lives a life of honesty, avoids vices, and follows societal rules is often said to be “on the straight and narrow.”