In depth Definition 1 of 2Pro Tip 1/3Research Context Use 'in depth' when describing extensive research or exploration of a topic. She is going in depth into renewable energy studies. Pro Tip 2/3Not Surface Level Implies going beyond superficial details to understand something complex. The documentary covers the issue in depth, not just the headlines. Pro Tip 3/3Time Investment Suggests dedicating a significant amount of time to thoroughly investigate something. I'll need to examine these findings in depth before deciding.