|Origin:||thorough 'through' (11-21 centuries), from through|
including every possible detail [↪ thoroughly]:
The doctor gave him a thorough check-up.
a thorough and detailed biography
The police investigation was very thorough.
thorough notes of the meeting
2 [not usually before noun]
careful to do things properly so that you avoid mistakes:
The screening of applicants must be thorough.
3 British English
used to emphasize the bad qualities of someone or something
—thoroughness noun [uncountable]