"tough", "rough", "though" and "borough" all come from Old English, without any French influence. The wackiness in pronouncing "ough" is sadly not predictable

"tough", "rough", "though" and "borough" all come from Old English, without any French influence. The wackiness in pronouncing "ough" is sadly not predictable from any set of rules and as you'd probably expect varies between dialects https://en.wikipedia.org/wiki/Ough_(orthography) https://en.wikipedia.org/wiki/Ough_(orthography)