DictionaryAI

fastidious

adjective
fa-STID-ee-uhs/fæsˈtɪdi.əs/

2 meanings of fastidious

Practice

  1. 1
    adjective
    Very careful about detail, accuracy, or cleanliness, and hard to please; demanding exacting standards and quick to notice what falls short.

    His fastidious nature showed in the way he lined up his shoes by color.

    She was fastidious about hygiene, scrubbing her hands for a full minute before handling any food.

    UsageOften fastidious about something: fastidious about hygiene. Less approving than meticulous, more refined than fussy.

    Similarmeticulous, fussy, particular, exacting, scrupulous

    Oppositecareless, sloppy, slovenly, lax

  2. 2
    biologyadjective
    Of a microorganism, having exact requirements for nutrients and for chemical and physical conditions, and especially being hard to grow in culture as a result.

    Haemophilus influenzae is a fastidious organism that grows only on enriched media such as chocolate agar.

    Fastidious species are easily missed in routine cultures, so clinicians may ask for molecular tests instead.

    Note

    In the lab the word describes rather than criticizes: a fastidious organism will not grow on ordinary media and needs enriched media, added growth factors or a special atmosphere such as extra carbon dioxide. It lives in set phrases such as fastidious organism and fastidious species, and the hardest of these organisms are often identified from their DNA instead of being grown.

    Checked 31 Oct 2026 · 3 facts

    • Fastidious organisms need special nutritional support rather than ordinary media. asset.ejaypee.com
    • Some fastidious organisms require an atmosphere enriched with carbon dioxide. wwwnc.cdc.gov
    • Difficult-to-grow fastidious bacteria can routinely be identified by detecting their DNA directly in specimens. depts.washington.edu

Practice

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Origin

Borrowed from Latin fastīdiōsus ("disdainful, scornful; disgusting"), from fastīdium ("loathing, disgust; niceness of taste"), perhaps from fastus ("disdain, haughtiness") + taedium ("disgust"). Compare French fastidieux.

Checked 31 Oct 2026 · 8 facts