Thorough

How to spell thorough

8 letters · 2 syllables

How to pronounce thorough

Say the part in capitals loudest.

What does thorough mean?

1. adjectiveDone completely and with great attention to detail, leaving nothing out.

Thorough in a sentence

• The accountant gave the records a thorough review before the audit.

• A thorough cleaning of the kitchen took most of the afternoon.

Where does thorough come from?

Language of origin: Germanic

Thorough began life as a stressed, emphatic form of the Old English word thurh, meaning 'through' or 'from end to end'. The same root sat behind the ordinary preposition 'through', and for centuries the two spellings drifted along together before settling into separate jobs: 'through' for passing from one side to the other, and 'thorough' for the idea of going completely through something, leaving nothing undone. By the late medieval period 'thorough' had taken on its modern sense of careful, complete and exhaustive, the quality of work that penetrates every corner. The troublesome -ough ending is a fossil: it once spelled a throaty sound (like the 'ch' in Scottish 'loch') that English later softened or dropped, which is why the letters no longer match the way the word is said. That mismatch, plus its close kinship with 'through' and 'though', is exactly what makes the spelling so easy to fumble.

How the word is built

• thorough (emphatic variant of Old English thurh: through, completely), the -ough spelling preserving the old guttural ending