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  • thorough
    thorough
    adjective
    executed without negligence or omissions.
  • Thorough
    Thorough
    noun
    thoroughgoing policy, as adopted in England by Strafford and Laud during the reign of Charles I
Synonyms

thorough

American  
[thur-oh, thuhr-oh] / ˈθɜr oʊ, ˈθʌr oʊ /

adjective

  1. executed without negligence or omissions.

    a thorough search.

    Synonyms:
    total, unqualified, sheer, downright, exhaustive, in-depth
    Antonyms:
    superficial, partial
  2. complete; perfect; utter.

    thorough enjoyment.

  3. extremely attentive to accuracy and detail; painstaking: a thorough analysis.

    a thorough worker;

    a thorough analysis.

  4. having full command or mastery of an art, talent, etc..

    a thorough actress.

  5. extending or passing through.


adverb

  1. Archaic. through.

noun

  1. (initial capital letter) the administrative policies of the Earl of Stafford and Archbishop Laud during the reign of Charles I: so called because they were uncompromisingly carried out.

thorough 1 British  
/ ˈθʌrə /

adjective

  1. carried out completely and carefully

    a thorough search

  2. (prenominal) utter

    a thorough bore

  3. painstakingly careful

    my work is thorough

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Thorough 2 British  
/ ˈθʌrə /

noun

  1. thoroughgoing policy, as adopted in England by Strafford and Laud during the reign of Charles I

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Other Word Forms

Etymology

Origin of thorough

First recorded before 900; Middle English (preposition and adverb); Old English thuruh, variant of thurh through

Explanation

Thorough describes something that is painstakingly complete, like a thorough search for your missing keys in which you look for them in coat pockets, under the table, in the refrigerator — in every single place you can think of. Thorough rhymes with "burrow": "THUR-oh." It looks a lot like through but remember thorough is an adjective, so you might use it to describe a thorough investigation or a thorough review. In contrast through is used most often as a preposition — you might look through every drawer, for example, in a search — or as an adverb — you might see a hole in your pocket where coins fall through.

Keep Reading on Vocabulary.com

Vocabulary lists containing thorough

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

"Thorough culling" to reduce the number of bears is the only effective way to reduce the risk for local people, researcher Ohnishi said.

From Barron's • Nov. 8, 2025

Thorough clinical trials have already proven benefits to heart health - and nausea is a known side-effect - but other findings will need to go through similar rigorous testing.

From BBC • Jan. 20, 2025

Thorough background checks have long been a norm used by incoming presidents when choosing their Cabinet.

From Salon • Nov. 25, 2024

Thorough research might also speed assistance to thousands of Americans who say they were injured.

From New York Times • May 3, 2024

Thorough in education, perfect in discipline, absolute in obedience—as yielding, as indestructible, as all-pervading as water or as air!

From To Cuba and Back by Dana, Richard Henry