October

October comes from Middle English, borrowed from Old French octobre, from Latin Octōber, meaning 'eighth month,' built from octō ("eight") plus the adjectival suffix -ber.

In the old Roman calendar, October really was the eighth month; when the calendar shifted and two months were added earlier in the year, October slid to tenth place but kept its original, now-mismatched name.

The octō at its root is the same 'eight' found in words like octagon and octopus, linking this month to anything built on that ancient number.