Meanings
prefix
- In the International System of Units and other metric systems of units, multiplying the unit to which it is attached by 10⁻¹⁵ (short scale quadrillionth or long scale billiardth).
Antonyms: peta-
Synonyms & antonyms
prefixIn the International System of Units and other metric systems of units, multiplying the unit to which it is attached by 10⁻¹⁵ (short scale quadrillionth or long scale billiardth).
Opposite
Origin
- Proto-Indo-European*pénkʷe
- Proto-Germanic*fimf
- Proto-Indo-European*déḱm̥
- Proto-Germanic*tehun
- Proto-Germanic*fimftehun
- Old Norsefimmtán
- Danishfemten
- Englishfemto-
From Danish femten (“fifteen”), with reference to the (negative) exponent in the relevant power of ten; the same principle also explains atto-.
More words from Danish
Full word history & related roots →Translations
Bulgarian фемто-
- фемто- (femto-)prefix
Chinese Mandarin 飞-
- 飞- (fēi-)prefix
Czech femto-
- femto-prefix
Danish femto-
- femto-prefix
Finnish femto-
- femto-prefix
French femto-
- femto-prefix
German femto-
- femto-prefix
Hungarian femto-
- femto-prefix
Icelandic femtó-
- femtó-prefix
Indonesian femto-
- femto-prefix
Japanese フェムト
- フェムト (femuto)prefix
Malay femto-
- femto-prefix
Polish femto-
- femto-prefix
Spanish femto-
- femto-prefix
Swedish femto-
- femto-prefix
Thai เฟมโต-
- เฟมโต- (feem-to-)prefix
Vietnamese fem-tô, phem-tô
- fem-tôprefix
- phem-tôprefix
Cite this entry
APA
femto-. (n.d.). In WatkinsX Dictionary. Retrieved November 4, 2026, from https://dictionary.watkinsx.com/word/femto-
MLA
“femto-.” WatkinsX Dictionary, https://dictionary.watkinsx.com/word/femto-. Accessed November 4, 2026.
Chicago
WatkinsX Dictionary, s.v. “femto-,” accessed November 4, 2026, https://dictionary.watkinsx.com/word/femto-.
Source: femto- on Wiktionary, CC BY-SA 4.0.