thorough

UK: /ˈθʌrə/ US: /ˈθɜroʊ, ˈθʌroʊ/ ,(thûr′ō, thur′ō)

WordReference Random House Learner's Dictionary of American English © 2026

thor•ough /ˈθɜroʊ, ˈθʌroʊ/   adj. 

1. done or accomplished without forgetting anything:
   a thorough search.
2. complete;
   perfect;
   utter:
   thorough enjoyment.
3. being very attentive to accuracy and detail:
   a thorough worker.

thor•ough•ly, adv. 
thor•ough•ness, n. [uncountable]

WordReference Random House Unabridged Dictionary of American English © 2026

thor•ough  (thûr′ō, thur′ō), adj. 

1. executed without negligence or omissions:
   a thorough search.
2. complete;
   perfect;
   utter:
   thorough enjoyment.
3. extremely attentive to accuracy and detail;
   painstaking:
   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.

adv., prep. 

6. [Archaic.] through.

n. 

7. World History (cap.) [Eng. Hist.] 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.

• bef. 900; Middle English (preposition and adverb, adverbial); Old English thuruh, variant of thurh through

thor′ough•ly, adv. 
thor′ough•ness, n. 
Synonyms

• 1. unqualified, total.

Antonyms

• 1. partial.

Collins Concise English Dictionary © HarperCollins Publishers::

thorough / ˈθʌrə/ adjective

1. carried out completely and carefully
2. (prenominal) utter: a thorough bore
3. painstakingly careful

Etymology: Old English thurh; related to Old Frisian thruch, Old Saxon thuru, Old High German duruh; see through

ˈthoroughly adverb

ˈthoroughness noun

WordReference Random House Unabridged Dictionary of American English © 2026

thor•o  (thûr′ō, thur′ō), adj., adv. 

1. an informal, simplified spelling of thorough.