Set forth Definition 1 of 3Pro Tip 1/3Journey Start Use 'set forth' when someone embarks on a significant or metaphorical journey, not a short trip. The explorers set forth into the unknown. Pro Tip 2/3Figurative Use 'Set forth' can also mean to embark on non-physical journeys, such as starting a project. We set forth on a journey of discovery within our company. Pro Tip 3/3Historic Flair Adds a sense of formality, importance, or historic significance to the start of a journey. They set forth to create a new nation.