Something that is difficult to understand; gibberish.

कुछ जो समझना मुश्किल हो; अस्पष्ट बातें।

English Usage: The lecture was so complex that it was all Greek to me.

Hindi Usage: वह व्याख्यान इतना जटिल था कि वह मेरे लिए तुच्छ बातें थी।