Let’s take a closer look.

1. thought - Adding a ‘t’ to -ough results in /ɔ:/, the aw sound in law, followed by a /t/ sound. The -gh is silent, so these words rhyme with port. This spelling is quite common in past simple verbs, for example bought, sought, caught. 
    

2. rough – /ʌ/, the uh sound in up, followed by an /f/ sound, resulting in words rhyming with stuff. For example, tough, enough
    

3. plough – /aʊ/,  the ow sound in now. This appears in some fairly uncommon words in English, for example, bough. It also appears with a final /t/ sound in drought, which rhymes with out.
    

4. through - / u:/, the oo sound in too. The -gh  is silent, so words like this rhyme with do
    

5. slough – in British English, the same as plough; in American English, like through. Another uncommon word, a slough means a place where the land is very muddy, like a swamp. 
    

6. though - /əʊ/, the oh sound in go. The -gh is silent, so words rhyme with so. For example, dough, although
    

7. lough - /ɒk/, the ock sound in lock, so this word sounds the same as ‘lock’. This is an old Irish word for a lake!
    

8. thorough - /ə/, In British English, the -ough isn’t stressed, and so becomes the weak schwa sound, like the -er in father. In American English, the -ough is pronounced /əʊ/, the oh sound in go. Another example of this pattern is borough.
    

9. cough - /ɒ/, the o sound in off, followed by an /f/. Rhymes with off, for example, trough
    

10. hiccough – more commonly spelt as ‘hiccup’, and pronounced with an /ʌ/, the ‘uh’ sound in ‘cup’

Confusing, isn’t it?!

Fortunately, you can pretty much ignore 5, 7, and 10, as they are very unusual words. 

That leaves us with 7 more frequent patterns that are useful to learn.

Can you think of more examples of words with each of these 7 sounds? 

Which sounds & spellings do you find most challenging?

Let us know in the comments!