Formative describes experiences, years, or influences that shape who someone becomes. Your formative years are typically childhood and adolescence, when your personality, values, and ways of thinking are still developing. A formative experience might be learning to play an instrument, moving to a new city, or overcoming a difficult challenge: something that changes you and helps make you who you are.

Think of clay being formed by a potter's hands. During your formative years, you're like that clay: still flexible, still taking shape. A great teacher during this time can be a formative influence, helping shape how you think about learning. A close friendship might be formative in teaching you about loyalty and trust.

When something is formative, it's actively forming you, building the foundation of who you'll become. That's why people often look back at their formative years and remember them so vividly: those experiences weren't just things that happened; they helped create the person looking back.