The characters combine to create a vivid metaphor: a person whose knowledge is as deep as an abyss (渊) and as broad as the horizon (博).
In Chinese culture, influenced heavily by Confucian values, scholarship and learning have been held in the highest esteem for millennia. The ideal figure was the scholar-official, a person who was not only a capable administrator but also a master of literature, history, and philosophy. 知识渊博 is the ultimate compliment for this type of intellectual pursuit. It reflects the cultural ideal of the 君子 (jūnzǐ), or “gentleman,” who is expected to be well-rounded, wise, and deeply educated. Comparison to Western Concepts: While an English speaker might call someone “an expert” or “a specialist,” these terms often imply deep knowledge in a narrow field. A physicist can be an expert in quantum mechanics but know little about Renaissance art. 知识渊博 is closer to the concept of a “polymath” or a “Renaissance man”—someone whose expertise spans multiple disciplines. It emphasizes a holistic, integrated wisdom rather than just specialized, technical skill. It's a compliment about the person's entire intellectual character.
This is a formal and highly respectful term. It is not used casually in everyday conversation.
You would not use it to describe a friend who is good at video games or a colleague who is quick with spreadsheets. For that, you would use a word like 聪明 (cōngmíng), meaning “smart” or “clever.”