Does -ough win for four-letter sequence with the most different pronunciations in English?
cough/thought
tough/enough
bough
dough/though
hiccough
(5)
You forgot
through
(6)
Then again so did Dr Seuss: http://www.amazon.com/Tough-Coughs-Ploughs-Dough-Writings/dp/0688065481
There are up to 10 depending on dialect. 6 are common in US English. You’re missing “through,” and “cough/thought” are different sounds. “Hiccough” isn’t common in US English, and there are other ones like “Scarborough” (-bruh).
“Slough” has 3 pronunciations depending on if you mean “to slide off,” “a swamp,” or a town.
Possibly. At least 6, BTW:
though the tough cough and hiccough plough me through
Slough (in one of its meanings) is pronounced “slew,” making six (although it can also be pronounced like “bough.”)
There’s a well-published historian and author named David McCullough. I don’t even knough hough to pronoughnce that.
ETA: I have a long-time friend from college days whose surname ends with -baugh. It took me a long time to become aware of how he pronounces that. In general, how many different ways might the be to pronounce people’s names ending in -ough and -augh?
cough/thought -aw (to me anyway :))
cough/thought -ah to someone else?
tough/enough -uff
bough/plough -ow
dough/though -oh
hiccough -up
through -oo
McCullough/Scarborough -uh
slough -ew
Huh, I only knew “slough” as sluff. I’ll take it!
Funny that three lazy words are based on ough, but different sounds:
doughnut - donut
hiccough - hiccup
through - thru
cough rhymes with off, and so deserves a line of its own.
“lough” is pronounced /lɒx/, so that’s another for the list.
Cite? I have slough rhyming with tough or bough but I never heard it as “slew”.
Merriam-Webster. It’s an American pronunciation.
Interesting. I always thought “slough” rhymes with “tough” was used for “comes off” or “peels off” and “slough” rhymes with “eww” was the inlet or body of water. Two different things I thought. I feel the need to argue with Merriam-Webster, for all of the good it will do me. 
If I’m reading correctly, you agree with M-W, their wording is just extra confusing.
Damn, is English an impossible language to learn! I hate it though I love its poetry!
Cough/off/thought all have an -aw sound for me. We will be caught in the caught/cot thingie. 
If “cough” has the same vowel sound as “off”, what vowel sound does “thought” have for you?
Aaaaaahhhhh!
Chough - pronounced chuff.
It’s not about the caught/cot merger. Where in the word “cough” do you see an “f”? Where in “thought” do you hear an “f”?
:smack: Thanks, got it. I was concentrating on the vowel sound only.
cough -off
thought -aw
tough/enough/chough -uff
bough/plough -ow
dough/though -oh
hiccough -up
through -oo
McCullough/Scarborough -uh
slough -ew
lough -ɒx
slight hijack: then there is always " ghoti ".
Here’s a relevant poem: The Chaos (aka English is Tough Stuff)