1. Highly significant or important especially bringing about or marking the beginning of a new development or era
   "epochal decisions made by Roosevelt and Churchill"
   - epoch-making

See also: epoch, important, significant

• four-wing flying fish
• four-year-old
• fourchette
• Fourdrinier
• fourfold
• fourfold point correlation
• fourhanded
• Fourier
• Fourier analysis
• Fourier series
• fourpence
• fourpenny
• fourpenny nail
• fourscore
• foursome
• foursquare
• fourteen
• fourteenth
• Fourteenth Amendment
• fourth
• Fourth Council of Constantinople
• fourth cranial nerve
• Fourth Crusade
• fourth deck
• fourth dimension