A "knowledge graph" in data science refers to a data structure that represents information in a graphical format, capturing relationships between entities. This structure enables the organization of complex data by illustrating how different concepts, individuals, or objects are interconnected. Knowledge graphs facilitate better semantic search, allowing algorithms to derive meaning from data rather than merely processing keywords. They enhance recommendations, improve decision-making, and support various applications in AI, such as natural language processing and machine learning. Overall, knowledge graphs are crucial for building intelligent systems that understand and relate to real-world entities.