The problem
Say them out loud: though (rhymes with go), through (rhymes with true), tough (rhymes with stuff) and thought (rhymes with taught).
The letters -ough are doing four different jobs — and there are even more if you add cough, bough and borough.
Why it happens
Old English had a throaty sound, a bit like the ch in Scottish loch, written with gh. Over centuries, different regions of England dropped or changed that sound in different ways.
Meanwhile, early printers froze the spelling before the pronunciation settled down. The result: spelling that remembers the past, and pronunciation that moved on without it.
The takeaway
When you see -ough, don't trust the letters. Learn each word as its own little character.
More weird English
- Why Is "Colonel" Pronounced "Kernel"?: another word where the spelling and the pronunciation come from two completely different places.