1. places, people, or things from which something comes or can be obtained
2. books, documents, or other materials that provide information for research or study
3. people who provide information, especially to journalists or researchers

Examples

• The company gets its materials from reliable sources.
• Students must cite their sources in research papers.
• Renewable energy sources include solar and wind power.
• The journalist protected her sources’ identities.
• Water sources in the region are becoming scarce.
• The historian consulted primary sources from the 1800s.
• Multiple sources confirmed the news story.