[more thorough; most thorough]
1 : including every possible part or detail
a thorough investigation/search
a thorough [=complete] examination
a thorough understanding of the rules and regulations
2 : careful about doing something in an accurate and exact way : METICULOUS
a thorough worker
The investigator will have to be thorough.
3 always used before a noun, chiefly British : complete or absolute
a thorough disgrace
a thorough mess/nuisance
— thoroughly adverb [more thoroughly; most thoroughly]
You've thoroughly [=completely] messed things up.
I thoroughly enjoyed the performance.
He studied the proposal very thoroughly.
That's been thoroughly documented/proven.
— thoroughness noun [noncount]