abecedism

Roughly a +‎ b +‎ c +‎ d +‎ -ism; compare abecedarium.

abecedism (plural abecedisms)

1. (rare) An initialism.
   • 1949 April 17, editorial in The Denver Post, quoted in Levette J. Davidson, “Folklore in Modern Speech”, in Louise Pound, “Miscellany”, in American Speech, Volume 25, Number 4, Duke University Press (December 1950), page 303,

     The tampering with our language, like so many other things, can be blamed on the Roosevelt new deal which created WPA, NRA, FDIC and so many other abecedisms.

   • 1969, Saul Galin with Peter Spielberg, Reference Books: How to Select and Use Them‎^[1], Random House, →LCCN, →OL, page 36:

     Contents: A key to over 45,000 acronyms (or initialisms or abecedisms), contractions, and similar condensed appellations.

   • 1996 February 21, “RossWilymz”, “Re: MENSA, a haven for people having trouble with English?”, in rec.org.mensa‎^[2] (Usenet), message-ID <4ggar6$ia3@newsbf02.news.aol.com>:

     "Brook" is a verb, H.M. (as in HMS) is a well-known abecedism (how do you look in a pinafore? don't answer), and we all know what a peter is -- […]

• This word is extremely rare.

• disbecame