initialysm: (noun)

[portmanteau of initially + initialism
 syllables: ini·​tial·​ysm
 pronunciation: i-ˈni-shə-ˌli-zəm (pronounced identically to "initialism")]

A word interpreted as an initialism that predates its own expansion; such a word that was born backwards. As in, "Initially it was just the initials, but later each letter was made to stand-in for a word for mnemonic effect."

Like a backronym, but is always pronounced as a series of letters.

The word initialysm was coined in order to explain the name of the aagg program, a command line program for use on Unix-like systems.

The name of the program is pronounced "a a gee gee", with the individual letters standing for the expansion phrase "AWS-a-go-go".

The program was initially named by finding a small number of characters that combined to form an easy to type, grep-friendly sequence on a standard QWERTY keyboard. Later, when it came time to document the program for use by others, the expansion phrase was retrofitted as a mnemonic device.