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

---

Thorough ² British  

/ ˈθʌrə /

noun

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

---

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.

Example Sentences

A statement went on to say a "thorough consultation process with parents, teachers, and young people themselves, is key to creating effective solutions to the problems associated with mobile phone use in schools."

From BBC • Apr. 22, 2026

"It underscores the importance of careful observation and thorough investigation of your data."

From Science Daily • Apr. 22, 2026

“The disparity continues,” said Rob Larew, president of the National Farmers Union, whose group claims Deere has made concessions like this before and that the promised software isn’t as thorough as what dealers use.

From The Wall Street Journal • Apr. 19, 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

It didn’t matter how thorough I had been about poking for clues—and make no mistake, I was thorough.

From "Simon vs. the Homo Sapiens Agenda" by Becky Albertalli

Related Words

• accurate
• careful
• complete
• comprehensive
• detailed
• exhaustive
• full
• intensive
• meticulous
• painstaking
• profound