thorough
Americanadjective
-
executed without negligence or omissions.
a thorough search.
- Synonyms:
- total, unqualified, sheer, downright, exhaustive, in-depth
- Antonyms:
- superficial, partial
-
thorough enjoyment.
-
extremely attentive to accuracy and detail; painstaking: a thorough analysis.
a thorough worker;
a thorough analysis.
-
having full command or mastery of an art, talent, etc..
a thorough actress.
-
extending or passing through.
adverb
noun
adjective
-
carried out completely and carefully
a thorough search
-
(prenominal) utter
a thorough bore
-
painstakingly careful
my work is thorough
noun
Other Word Forms
- quasi-thorough adjective
- quasi-thoroughly adverb
- superthorough adjective
- superthoroughly adverb
- thoroughly adverb
- thoroughness noun
- unthorough adjective
- unthoroughly adverb
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.
Vocabulary lists containing thorough
"Earth and Space"
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Harry Potter and the Prisoner of Azkaban
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Everything, Everything
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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.
“We are conducting a thorough investigation with leading third-party forensics experts and are communicating directly with affected stakeholder groups as we have findings,” it said.
From The Wall Street Journal • Apr. 23, 2026
They had undergone a hard and thorough lesson in geography in their late teens and twenties, and certainly understood the location and significance of the Philippines, Iwo Jima, Tunisia or Normandy.
From Salon • Apr. 19, 2026
"We have evacuated the school and will carry out a thorough investigation into this tragic incident," he added.
From Barron's • Apr. 14, 2026
National Farmers Union North Regional Board Chair and a farmer himself William Maughan said "thorough, meaningful and clear" engagement with farmers was crucial for the project's success.
From BBC • Apr. 11, 2026
Mom decided that before she could get down to any serious painting, she needed to compile a thorough art reference library.
From "The Glass Castle" by Jeannette Walls
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
