thorough

1 of 3

adjective

thor·​ough ˈthər-(ˌ)ō 

sometimes ˈthȯr-;

ˈthə-(ˌ)rō

1

: carried through to completion : exhaustive

a thorough search/examination/investigation

2

a

: including every possible part or detail

a thorough description

a thorough understanding of the rules and regulations

b

: careful about detail : painstaking

a thorough scholar

c

chiefly British : complete in all respects

thorough pleasure/disgrace

a thorough mess/nuisance

d

: having full mastery (as of an art)

a thorough musician

thoroughness noun

thorough

2 of 3

preposition

archaic

: through

thorough

3 of 3

adverb

archaic

: through

Synonyms of thorough

Adjective

• complete
• simple
• unconditional
• sheer
• utter
• pure
• absolute
• total
• definite
• very

Examples of thorough in a Sentence

Adjective

… one realized that it was the restaurant's thorough and even comic Frenchness that had made it so entirely New York. —Adam Gopnik, New Yorker, 22 Mar. 2004

Bruce tells me to squat down and Koani sidles up, ears flattened, tail tucked away, and gives my face a thorough licking. —Nicholas Evans, Daily Telegraph, 26 Sept. 1998

The job was uncharacteristically thorough for a Russian contract killing—three different types of bullets riddled Mikho's body. —New Republic, 15 Dec. 1997

a thorough understanding of the rules and regulations

The investigator will have to be thorough.

Recent Examples on the Web

Adjective

In late 2016, for example, the President’s Council of Advisors on Science and Technology issued the first thorough, unclassified warning about the potential national security risks posed by biotechnology. — Elizabeth Sherwood-Randall, Foreign Affairs, 18 Aug. 2026

In IconArrows pointing outwards BCA Research The data come from a thorough and provocative new report by BCA's longtime (and now semi-retired) chief economist Martin Barnes. — Michael Santoli, CNBC, 17 Aug. 2026

For companies without a data retention plan, a thorough data inventory often uncovers personal information that has been accumulating across systems for years. — Jodi Daniels, Forbes.com, 17 Aug. 2026

Initially, patients should have a thorough conversation with their physicians about the benefits and risks of GLP-1s — especially if patients are broadly healthy and are interested in the drugs for mostly cosmetic reasons. — Jessica Starr, Fortune, 14 Aug. 2026

Word History

Etymology

Preposition, Adjective, and Adverb

Middle English thorow, from Old English thurh, thuruh, preposition & adverb

First Known Use

Adjective

15th century, in the meaning defined at sense 1

Preposition

before the 12th century, in the meaning defined above

Adverb

before the 12th century, in the meaning defined above

Phrases Containing thorough

• thorough-paced

Rhymes for thorough

• boro
• burro
• burrough
• burrow
• furrow
• yarborough

Kids Definition

thorough

adjective

thor·​ough

ˈthər-ō, 

ˈthə-rō

1

: marked by or carried out to completion : exhaustive

a thorough search

2

: careful about detail

a thorough worker

thoroughly adverb

thoroughness noun

Etymology

Adjective

Middle English thorow "thorough," from Old English thuruh, thurh "through" — related to thrill, through see Word History at thrill