English

femtometre

From femto- + metre.

A compound of femto- + metre

Proto-Germanic *fimftehun ‘fifteen’

Old Norse fimmtán ‘fifteen’

Danish femten ‘fifteen’

Proto-Indo-European *meh₁- ‘to measure’

Ancient Greek μέτρον ‘measure, rule, length, size, poetic metre’

Latin metrum

French mètre ‘metre/meter’

English metre

Today it means

noun An SI unit of length equal to 10⁻¹⁵ metres. Symbol: fm

Language periods are conventional ranges, not dates for this word.

Etymograph / femtometre