Where does “femto-” come from?

femto- (Danish) comes from Danish femten, from Old Norse fimmtán, from Proto-Germanic fimftehun, from Proto-Germanic tehun, from Proto-Indo-European déḱm̥t — ten.

femto- (Danish): femto- (SI prefix for 10-15)

Definitions

  1. femto- (SI prefix for 10-15)

Ancestry of “femto-”, step by step

StepLanguageWordMeaning
1Danishfemtenfifteen
2Old Norsefimmtánfifteen
3Proto-Germanicfimftehunfifteen
4Proto-Germanictehunten
5Proto-Indo-Europeandéḱm̥tten
Every word from Proto-Indo-European déḱm̥t →Every word from Proto-Germanic tehun →Every word from Proto-Germanic fimftehun →