1. of great importance; marking a significant period or turning point in history or development

Examples

• The invention of the printing press was an epochal event that transformed human civilization.
• The moon landing in 1969 was considered an epochal achievement in space exploration.
• The fall of the Berlin Wall marked an epochal shift in world politics.
• The discovery of penicillin was epochal for modern medicine.
• Social media has had an epochal impact on how people communicate.
• The Civil Rights Act of 1964 was an epochal piece of legislation in American history.