According to the ONLINE ETYMOLOGY DICTIONARY**, the etymological “definition” of the indefinite article “a” is:
a form of an used before consonants, mid-12c., a weakened form of Old English an “one” (see an). The disappearance of the -n- before consonants was mostly complete by mid-14c. After c. 1600 the -n- also began to vanish before words beginning with a sounded -h-; it still is retained by many writers before unaccented syllables in h- or (e)u- but is now no longer normally spoken as such. The -n- also lingered (especially in southern England dialect) before -w- and -y- through 15c.
It also is used before nouns of singular number and a few plural nouns when few or great many is interposed.
For reasons unclear, I wondered all of a sudden how that much overworked and under-appreciated word “a” came about…
*Or should the heading instead read: “An” History of A?
**You probably know this already, however, I’ll include it anyway just to kill time and fill space and provide the illusion of an intellect. Anyway, despite its name being ONLINE ETYMOLOGY DICTIONARY, according to Merriam-Webster (and, in all fairness, the ONLINE ETYMOLOGY DICTIONARY’s main page as well), etymology is concerned not so much for the definition of a word, but instead its concern is mostly with the history of the linguistic form of…
Heck, instead of me bumbling through with a paraphrase of the definition of the word etymology and risking the high probability of screwing it up, I’ll continue to take the lazy route as I did above and just cut and paste the sucker:
Definition of etymology
1 : the history of a linguistic form (such as a word) shown by tracing its development since its earliest recorded occurrence in the language where it is found, by tracing its transmission from one language to another, by analyzing it into its component parts, by identifying its cognates in other languages, or by tracing it and its cognates to a common ancestral form in an ancestral language
2 : a branch of linguistics concerned with etymologies
***Yeah, so, anyway…