Are initialisms that sound like existing words in English still called initialisms? Or are they called something else?
An initialism has come into common parlance as a word on its own.
An initialism is a word made from the first letters of each word in a phrase. Unlike acronyms, initialisms cannot be spoken as words: they are spoken letter by letter.
These are examples of initialisms:
- DVD (Digital Versatile Disc)
- CPU (Central Processing Unit)
- CD (Compact Disc)
Is initialism the correct term for the small set of initials that, when spoken aloud letter by letter, sound like existing words in English?
Examples:
- The initials D.K. when spoken aloud sound like the word "decay"
- The initials M.T. when spoken aloud sound like the word "empty"
- The initials C.D. when spoken aloud sound like the word "seedy"
Is "D.K." in this usage an initialism? If not, is it called something else?
I have read this question and I do not believe this is a duplicate. I am not asking about the existing words okay nor emcee which start from the initialisms and have become accepted spelled-out words. I am starting from the accepted words and wondering about the matching initials.
As long as each of the letters stands for the initial letter of a word, they're still called initialisms (or acronyms, unless you're a pedant about the definition of that word). So as you say, CD is an initialism (acronym) for "compact disc".
Actually, none of the examples that you gave is pronounced exactly like the corresponding non-initialism. They are stressed differently: initialisms tend to have some stress on each syllable, with the last syllable taking the primary stress by default (for more on this, see my answer to Why are all acronyms accented on the last syllable?). D.K., M.T., C.D. are pronounced /ˌdiˈkeɪ/, /ˌɛmˈti/, /ˌsiˈdi/; decay, empty, seedy are pronounced /dɪˈkeɪ/, /ˈɛmti/, /ˈsidi/.
There are exceptions to that stress pattern for initialisms; e.g. I pronounce "DJ" (for "disc jockey") as /ˈdi(ˌ)dʒeɪ/.
If you use "MT" simply as a shortened spelling of the word empty, it would not be an initialism. I don't know of a special term for that kind of shortened spelling; it would be a type of abbreviation.