vigesimal

The story

1. Proto-Indo-European · derived from*wi(h₁)ḱm̥ttós
2. Latin · derived fromvīgintī“twenty”
3. Latin · derived fromvīcēsimus“twentieth”
4. Latin · derived fromvīgēsimus“twentieth”
5. English todayvigesimal

From Latin vīgēsimus (“twentieth”), variant of Latin vīcēsimus (“twentieth”), from Latin vīgintī (“twenty”), (from *vīcēnssos, from Proto-Indo-European *wi(h₁)ḱm̥ttós, with the -imus ending of decimus (“tenth”)) + -al (suffix forming an adjective). Compare Latin vīgintī (“twenty”), from Proto-Indo-European *h₁wih₁ḱm̥ti, from *dwi(h₁)dḱm̥ti(h₁), *dwi(h₁)dḱm̥ti (“two tens; two decades”).

Words from the same roots

First known use, by meaning

• from mid-17th c. Occurring in intervals of twenty.
• from mid-17th c. To the base twenty.