Attosecond

noun

noun ·Rare ·Advanced level

Definitions

Noun
  1. 1
    An SI unit of time equal to 10⁻¹⁸ seconds. Symbol: as

    "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"

  2. 2
    one quintillionth (10^-18) of a second; one thousandth of a femtosecond wordnet

Synonyms

All synonyms
as

Example

More 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"

Etymology

From atto- + second.

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Data sourced from Wiktionary, WordNet, CMU, and other open linguistic databases. Updated March 2026.