Substance is the physical material that something is made of. A wooden desk has wood as its substance, while a bronze statue has bronze as its substance. Scientists talk about different substances when they study materials like water, salt, iron, or oxygen.

The word also means the essential or most important part of something. When a teacher asks for the substance of a story, she wants you to explain the main ideas, not every tiny detail. A speech with substance contains real, meaningful content rather than just fancy words. If someone says “style over substance,” they mean something looks good on the surface but lacks real value or depth underneath.

In everyday conversation, you might hear people talk about someone being a person of substance, which means they have depth, character, and real accomplishments rather than just appearances. A substantial amount means a large or significant quantity: substantial homework means you'll be busy for a while.

The word connects to being real and solid rather than empty or fake. A substantive discussion tackles important issues seriously, while a substantial meal fills you up. When something has substance, it has weight and meaning, whether that's physical weight or the weight of importance.