c. 150 BCE
Polybius: a Roman military punishment selecting as near as possible one tenth.
A word with survivors
The Nine Who Walked Away
Everyone "knows" the pedant's rule: decimate means to destroy exactly one in ten, and using it for devastation is modern corruption. The pedant is half-wrong twice over. The Roman tenth is real. So is the broad sense, attested from the 1660s.
First, set what the word feels like to you. The cohort will answer with the older arithmetic.
You pictured 80%. Rome marks 10.0%. The gap is 70 percentage points.
Selected by lot48 fall
The rest432 walk away
Split10.0% / 90.0%
every tenth selectednine of ten survive
Polybius describes the tribune choosing by lot numbers adjusted to form "as near as possible" the tenth part of the offenders. That qualifier matters. The display uses tidy unit sizes so its tenth is exact; the source describes an approximation where headcounts demanded it. The terror reached everyone because nobody knew whose lot would fall.
The supposedly modern meaning
Sort the record by date or by meaning. The broad destructive sense is not internet slang. Its attestation is already in the seventeenth century.
c. 1600
English literal sense: select by lot and put to death every tenth man, dated by Etymonline.
1655
Decimation tax: a ten percent levy associated with Cromwell's rule of the major-generals.
1660s
Broad English sense: destroy a large but indefinite number, dated by Etymonline.
2026 - 1660 = 366 years, about 360 years.
The check
The page recomputes the current unit split, your intuition gap, and the elapsed time from the opening of the attested decade:
480 / 10 = 48 selected
480 - 48 = 432 survivors
48 / 480 = 10.0% selected
432 / 480 = 90.0% survive
2026 - 1660 = 366 years (about 360)
Free choices and uncertainty: 480 is a display choice, as are the other clean multiples of ten. Polybius says "as near as possible," so exactness belongs to this clean model, while the historical rule is a tenth with practical rounding. "1660s" is decade-level attestation, not a precise first-use year; subtracting its opening year gives 366, rounded down by decades to "about 360." An attestation is evidence of use by then, not the word's birthday.
The verifier independently derives each displayed result and exits zero only if every check passes: node research/does-decimate-mean-one-in-ten/verify-does-decimate-mean-one-in-ten.mjs.
What the page proves, and what it does not
Proven by the cited record: Polybius describes selecting near a tenth; Etymonline dates the English military sense to c.1600 and the broad sense to the 1660s; Merriam-Webster accepts both historical and broad senses; the 1655 fiscal levy was ten percent.
Not proven here: that Roman decimation was routine. Modern scholarship disputes its frequency and notes legendary material in the tradition. The page demonstrates the definition, not prevalence. It also does not assign a casualty count to Crassus's use during the Spartacus revolt, where ancient accounts and modern reconstructions differ.
A narrowed claim: the surviving nine could still receive collective punishment, including barley rations and camping outside the protected camp in Polybius. "Walk away" means not selected for the lethal tenth, not unharmed or simply released.