A bright-line rule is a clear and concise legal principle. It provides definite guidelines for decision-making, leaving no room for ambiguity. Other words that can be used as synonyms for bright-line rules include clear-cut, explicit, definite, unambiguous, decisive, and precise. These terms emphasize the clarity and certainty that such rules provide. In contrast, vague and flexible rules can create confusion and uncertainty. Bright-line rules are especially important in legal contexts to ensure fairness and consistency in decision-making. They are widely used in various fields, such as finance, business, and ethics, to establish clear and unambiguous guidelines.