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Through, though, or thorough
They look almost alike: through means from one side to the other, though means although, and thorough means careful and complete.
Quick rule
From one side to the other, or start to finish? Through. Could you say although or however? Though. Careful and complete? Thorough.
From one side to the other (through the tunnel), or from start to finish (through the night).
Although (though it was late), or at the end of a sentence, after a comma, meaning however: It's nice, though.
Done completely and carefully: a thorough check. It has two syllables.
How to choose
| Question | through | though | thorough |
|---|---|---|---|
| Does it mean from one side to the other, or start to finish? | Yes | No | No |
| Could you say although or however instead? | No | Yes | No |
| Does it describe something careful and complete? | No | No | Yes |
Why it trips people up
Through, though, and thorough share almost every letter, and -ough is pronounced differently in each: /θruː/, /ðoʊ/, /ˈθɜːroʊ/. One missing letter turns a real word into another real word, so spell-checkers rarely catch the slip.
How they sound
Through is /θruː/, though is /ðoʊ/ (British /ðəʊ/), and thorough has two syllables: /ˈθɜːroʊ/ in American English, /ˈθʌrə/ in British.
- through/θruː/
- though/ðoʊ/
- thorough/ˈθɜːroʊ/
How each one works
Through
From one side to the other
We drove through the tunnel.
Across an opening
She looked through the window.
From start to finish
The baby slept through the night.
Though
Although, at the start
Though it was cold, we swam.
At the end: however
It's expensive. I love it, though.
Even though: stronger
He smiled even though he was sad.
Thorough
Done carefully
The doctor did a thorough exam.
A careful person
She is very thorough in her work.
Complete
The kitchen needs a thorough cleaning before the party.
Common mistakes
Wrong: The police did a through search.
Right: The police did a thorough search.
Thorough (careful, complete) has two syllables; through is a preposition.
Wrong: Are you though with the newspaper?
Right: Are you through with the newspaper?
Be through with (finished using it) needs the r of through.
Memory trick
Through has an r right after th, like running from one side to the other. Though has no r and is short. Thorough has an extra o and two syllables: it is longer because it checks everything.
It depends
- Thru and tho
- Thru and tho are old informal variants, seen mostly in casual writing and signs (drive-thru). In formal writing, use through and though.
- Thorough vs throughout
- Throughout means in every part or during the whole time (throughout the year). Thorough is an adjective: a thorough review.
FAQ
Through or though: what's the difference?
Through (with an r) is movement or time from one side to the other: through the door. Though means although: though it was late.
Thorough or throughout?
Thorough is an adjective, careful and complete: a thorough review. Throughout means everywhere in something or during all of it: throughout the year.