Standard Lemma guide

attosecond

noun · 2 senses · updated from the 2026-07-25 local source snapshot

Definitions and examples are grouped by meaning. Pronunciation, history, word forms, translations, descendants, synonyms, antonyms, derived terms, and related words appear whenever the source provides them.

Sound

Pronunciation

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1

noun

Meaning 1

An SI unit of time equal to 10−18 seconds. Symbol: as

Definition source: English Wiktionary via Wiktextract

Topics: metrology

Examples

  • Holonyms: femtosecond < picosecond < nanosecond < microsecond < millisecond < centisecond < decisecond < second < decasecond < minute < hectosecond < kilosecond < hour < day < week < megasecond < fortnight < month < year < gigasecond < century < kiloannum, kiloyear, millennium < terasecond < mega-annum, megayear < petasecond < giga-annum, gigayear < exasecond < zettasecond < yottasecond < ronnasecond < quettasecond
  • Meronyms: quectosecond < rontosecond < yoctosecond < zeptosecond

Meaning relationships

Synonyms: none provided

Antonyms: none provided

2

noun

Meaning 2

one quintillionth (10^-18) of a second; one thousandth of a femtosecond

Definition source: Princeton WordNet 3.0

No example sentence was provided for this meaning.

Meaning relationships

Synonyms: none provided

Antonyms: none provided

Broader terms: time unit, unit of time

History

Etymology

From atto- + second.

Across languages

Translations

9 source translations are retained for this English entry.

  • Chinese Mandarin: 阿秒 (āmiǎo) — unit of time, equal to 10−18 second
  • Chinese Mandarin: 阿托秒 (ātuōmiǎo) — unit of time, equal to 10−18 second
  • Dutch: attoseconde — unit of time, equal to 10−18 second
  • Georgian: ატოსეკუნდი (aṭoseḳundi) — unit of time, equal to 10−18 second
  • Georgian: ატოწამი (aṭoc̣ami) — unit of time, equal to 10−18 second
  • Hungarian: attoszekundum — unit of time, equal to 10−18 second
  • Polish: attosekunda — unit of time, equal to 10−18 second
  • Swedish: attosekund — unit of time, equal to 10−18 second
  • Ukrainian: аттосекунда (attosekunda) — unit of time, equal to 10−18 second