* Old English: The word originally came from Old English "coh", pronounced similar to the modern word "cough".
* Middle English: In Middle English, the word evolved to "coughen", likely due to the influence of similar-sounding words ending in "-en".
* Modern English: Over time, the "-en" ending was dropped, leaving us with "cough".
It's believed the change in spelling and pronunciation reflects the natural evolution of language, where words shift and adapt over time. There's no single definitive reason why it's spelled "cough" – it's simply how the word evolved.
Interestingly, the sound "gh" in "cough" isn't pronounced like it is in words like "ghost" or "laugh". This further adds to the peculiarity of the spelling.