The tenth day of the ten-day week in the French Revolutionary calendar, marking the end of each ten-day cycle.
From French 'décadi' from Latin 'decad-' (ten). During the French Revolution, the Gregorian calendar was replaced with a rational metric calendar featuring ten-day weeks, and 'decadi' was the final day of each cycle.
The French Revolutionary calendar was brilliantly logical—ten-day weeks meant three weeks per month for perfectly rational organization—but it failed because humans are biologically and religiously tied to seven-day weeks, proving that logic alone can't override human nature.
Complete word intelligence in one call. Free tier — 50 lookups/day.