The term 'fundamental' can be defined in many ways, including through the crossword solutions of LAW (3 letters), NATURAL (7 letters), CONSTITUTIONAL (14 letters), ESSENTIAL (9 letters), INHERENT (8 letters), KEY (3 letters), CORE (4 letters), ROOT (4 letters), BASAL (5 letters), BASIC (5 letters), PRIMAL (6 letters), CARDINAL (8 letters), GRASSROOT (9 letters), UNDERLYING (10 letters), and MEATANDPOTATOES (15 letters). These words all refer to something that is ESSENTIAL, BASIC, or necessary for something else. For example, LAW refers to the rules and regulations that govern a society, while NATURAL refers to something that is part of nature. CONSTITUTIONAL refers to something that is based on a constitution, such as a country's laws, while ESSENTIAL refers to something that is absolutely necessary. INHERENT refers to something that is an INHERENT part of something else, while KEY refers to something that is important or ESSENTIAL. CORE and ROOT both refer to the most BASIC part of something, while BASAL and BASIC refer to something that is fundamental or ESSENTIAL. PRIMAL and CARDINAL both refer to something that is primary or ESSENTIAL, while GRASSROOT and UNDERLYING refer to something that is fundamental or BASIC. Finally, MEATANDPOTATOES refers to something that is ESSENTIAL or BASIC, like the main ingredients of a meal. All of these words refer to something that is fundamental or ESSENTIAL in some way.