Thorough means complete and careful, missing no detail. A thorough search, a thorough job, thorough preparation.
It is high praise for work and describes the person as much as the result: she is thorough. It is pronounced THUR-uh in British English and THUR-oh in American, which is one of the sharper pronunciation differences between them. Note thoroughly, the adverb; thoroughbred, meaning a pedigree horse; and thoroughfare, meaning a road running right through — the same through inside all of them.
1adjectivethoroughComplete and careful, missing no detail.
“It was a thorough job and it took about three times as long.”
synonyms: exhaustive, meticulous
thorough is a quality of completeness.
Thorough and through are the same Old English word, thuruh. They split into two spellings and two jobs in Middle English — one a preposition, one an adjective — and the meaning of complete passage runs through both.
Proto-Indo-European
*terh₂-
Old English
þuruh
Middle English
thoruȝ
English, today
thorough
From Middle English thoruȝ, þoruȝ, from Old English þuruh, a byform of Old English þurh, whence comes English through. The adjective derives from the preposition and adverb. The word developed a syllabic form in cases where the word was fully stressed: when it was used as an adverb, adjective, or noun, and less commonly when used as a preposition.
Etymology from Wiktionary, CC BY-SA