femtosecond.
An SI unit of time equal to 10⁻¹⁵ seconds. Symbol: fs
Meaning & usage
An SI unit of time equal to 10⁻¹⁵ seconds. Symbol: fs
Where this word comes from
Etymology tree Proto-Indo-European *pénkʷe Proto-Germanic *fimf Proto-Indo-European *déḱm̥ Proto-Germanic *tehun Proto-Germanic *fimftehun Old Norse fimmtánder. Danish femtender. English femto- English second English femtosecond From femto- + second.
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Definitions, grammatical labels, IPA, etymology and examples: Wiktionary contributors, extracted by Kaikki / Wiktextract. Adapted under CC BY-SA 4.0. Selected fields and authored examples are shown; third-party quotations and audio are omitted. See contributor history.
Last enriched 2026-09-10. Definitions are in English. Romanizations are shown when supplied by the source; syllable estimates are omitted for unsupported scripts.