1. a particular kind of matter with uniform properties
2. the most important or essential part of something
3. meaningful content or ideas; depth of thought

Examples

• The scientist analyzed the unknown substance in the laboratory.
• Water is a substance composed of hydrogen and oxygen.
• The substance of his argument was that taxes should be lowered.
• Her speech lacked substance and failed to convince the audience.
• The novel has real substance, dealing with important social issues.
• He inherited property of considerable substance from his grandfather.
• The committee focused on the substance of the proposal rather than minor details.