This section needs expansion with: details on the sound changes that occurred after Middle English to the present day. You can help by adding to it. Relevant discussion may be found on the talk page.(May 2022)
Rhymes with off, scoff. Trough is pronounced /trɔːθ/ (troth) by some speakers of American English, and a baker's trough is also pronounced /troʊ/ in that variety.[2]
Rhymes with caught, taught. Regularly so used before /t/, except in doughty/ˈdaʊti/ and drought/draʊt/. Realized as /ɒ/ or /ɑː/ in dialects exhibiting the cot-caught merger.
Pronounced /oʊ/ when at the end of a word in American English (borough and thorough thus rhyme with burrow and furrow), but reduced to /ə/ when followed by another syllable in many dialects (such as in thoroughly).
An example sentence using the nine pronunciations commonly found in modern usage (and excluding hough, which is now a rarely used spelling) is, "The wind was rough along the lough as the ploughman fought through the snow, and though he hiccoughed and coughed, his work was thorough."
Another, slightly shorter example would be, "The rough, dough-faced ploughman fought through the borough to the lough, hiccoughing and coughing."
Other pronunciations can be found in proper nouns, many of which are of Celtic origin (Irish, Scottish or Welsh) rather than English. For example, ough can represent /ɒk/ in the surname Coughlin, /juː/ in Ayscough,[4] and /i/ in the name Colcolough (/ˈkoʊkli/) in the United States.[5]
Tough, though, through and thorough are formed by adding another letter each time, yet none of them rhyme (in American English, however, though and thorough both have /oʊ/).
Some humorous verse has been written to illustrate this seeming incongruity:
"A rough-coated, dough-faced ploughman strode, coughing and hiccoughing, thoughtfully through the streets of Scarborough."[9]
Because of the unpredictability of the combination, many English spelling reformers have proposed replacing it with more phonetic combinations, some of which have caught on in varying degrees of formal and informal success. Generally, spelling reforms have been more widely accepted in the United States and less so in other English-speaking areas. One problem is that a pronunciation with the velar fricative is still found locally in parts of North-East Scotland, where, for example, trough is pronounced /trɔːx/.[citation needed]
In 18th century British English, before the cheap Penny Post and while paper was taxed, the combination ough was occasionally shortened to ô when the gh was not pronounced, to save space: thô for though, thorô for thorough, and brôt for brought.[citation needed]
^Bolton, H. Carrington (1891). "The Pronunciation of Folk-Names in South Carolina". The Journal of American Folklore. 4 (14): 270–272. doi:10.2307/534017. JSTOR534017.