the.com/thirty

The age where you stop counting birthdays and start counting regrets and retirement funds.

means The cardinal number equal to three tens — and the age that culturally marks the exit door from youth.

from From Old English 'þritig,' built from 'þri' (three) plus '-tig,' a suffix meaning 'group of ten' (the same piece that gives us forty, fifty, and the rest). So thirty is literally 'three tens' — a tidy bit of Germanic arithmetic baked right into the word, long before it picked up its modern reputation as the age of reckoning.

tennis score
thirty means one point, not thirty points
flirty saying
pairs with thirty to rhyme regret into a compliment
journalism sign-off
dash-30-dash once meant the story ends
days hath
only four months actually have thirty days
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