Why is “colonel” pronounced like “kernel”?
The Real Answer
Colonel is pronounced roughly like kernel because English inherited two different stages of the word’s history. The word traces through Italian colonnello, but French developed a form spelled coronel, with an r, and English adopted that pronunciation.
Later, the English spelling was changed back toward the Italian-looking colonel, while the older r-based pronunciation survived. Over time that pronunciation compressed into the modern English sound we write informally as kernel.
So the spelling and pronunciation look mismatched because they are historical leftovers from different versions of the same borrowed word, not because the letters in modern colonel follow ordinary English sound rules.
Colonel is one of those words you learn by hearing it first and regret the second somebody asks you to spell it. You say it confidently, start writing, get halfway through, and suddenly you’re looking for a different word that means the same thing.
Why People Ask This
People ask because the spelling gives almost no warning that an r sound is coming. Unlike many irregular English words, the mismatch is large enough that learning the pronunciation does not make the written form feel more intuitive; it makes the word look as though two different histories were glued together.