Question

Silent letter in the word colonel

Answer 1

The silent letter in the word colonel is its third letter ‘l’.

The phonetic transcription of the word given in the Oxford Dictionary is /ˈkəːn(ə)l/. It is quite readable that the word which has been omitted in the process of phonetic transcription is its third letter ‘l’. Therefore, ‘l’ becomes silent in this case.  

Furthermore, while explaining the etymological development of this word, Oxford Dictionary informs, “The form coronel, source of the modern pronunciation, was usual until the mid of 17th century.”  

Answer 2

There is no silent letter in the word colonel.  

Here the word sounds like r. This is a clear case of dissimilation of spelling.

The origin of this strange pronunciation starts in the middle Ages in Italy, where a military officer used to be addressed   officially as “colonello.”

Then, later the French borrowed that word and they changed it to “coronel”, which in English it was spelled as Colonel with the French pronunciation.