www.alphadictionary.com

Colonel: the military rank. Why, also, is it pronounced with the
letter "r', when there is none in the word.

I second that motion. I do have the impression that somewhere in the British Empire at sometime the word Was pronounced with three syllables including the L. I may be wrong.

Normally the villain in a bad spy movie pronounces it tri-syllabically, in a bad foreign accent. Not sure why.

'Ahh, Col-oh-nell, I've been expecting you.'

Good choice, if not as inexplicable as lieutenant.

Here is etymonline's explanation:
https://www.etymonline.com/word/colonel

It seems the English could not make up their minds between the French 'r' and the original Latin/Italian 'l'.

It is an interesting question how spelling and pronunciation can go different ways like this, and why some languages (notably English) are especially prone to such mismatches.

Thanks, you all. I appreciate your feedback.
We could piggy-back "lieutenant", probably 'place-holder'
or some such. But the British 'leftenant (?) has me
baffled as well.

Lieutenant is the word I was referring to, it's spelled the same in British English, but pronounced correctly (if inexplicably).

So British English spells the word "lieutenant", but pronounces
it as "leftenant"? Am I understanding you correctly?

Yes, that's right

Yes, perhaps lieutenant as a place-holder is a rank held in an 'acting' role while the serious officers are away. In the British army anyway, lieutenant is the lowest commissioned rank so presumably a sergeant or similar was co-opted to the role after the captain had been shot?

Yup, your thoughts make perfect sense to me, exactly the
way I'd picture it, know as little as I do of the military.

Thanks too, Iain for clearing up the lef business for me.

Here's what the good Dr. has to say on the subject.