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

McCartney 3, 2, 1 wasn’t exclusively aimed at music nerds, but a certain measure of nerdiness was ideal for appreciating the six-episode deep dive, which featured thorough lyrical analysis and ruminations on a unique journey. — Daniel Fienberg, HollywoodReporter, 17 Sep. 2026

The complaint claims that after Lipps was identified as a lead, Heck did not conduct a thorough investigation or find sufficient probable cause before requesting an arrest warrant. — Meredith Deliso, ABC News, 17 Sep. 2026

These can become a safety hazard if the mower turns them into projectiles, so a thorough raking before mowing is a good precaution. — Luke Miller, Better Homes & Gardens, 16 Sep. 2026

As with many a Mamdani initiative, the plan calls on the city to address the affordability of those modes — setting a goal of more affordable Citi Bike access and more thorough transit discounts for New Yorkers in need. — Evan Simko-Bednarski, New York Daily News, 15 Sep. 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