What's the origin of "さ", the nonsubjective (dunno how to call it nominalizer)


So, I know that the subjective nominalizer み comes from the
imperfective/irrealis form of む, apparently the subjective particle that makes
things into subjective verbs?? I just heard this on a website. But if that
exists... Then what does さ come from? Unless it doesn't have an origin. My
closest guess is the su in suru but it doesn't really make any sense.




As @EiríkrÚtlendi suggests, 日本国語大辞典 contains a more explicit entry on the
etymology, but essentially the same:

>
> サマ（様）の反〔[名語記](https://ja.wikipedia.org/wiki/%E5%90%8D%E8%AA%9E%E8%A8%98)・[大言海](https://kotobank.jp/word/%E5%A4%A7%E8%A8%80%E6%B5%B7-91059)〕

反 should mean 略 ([source](https://kotobank.jp/word/%E5%8F%8D-563548))




As @EiríkrÚtlendi suggests, 日本国語大辞典 contains a more explicit entry on the
etymology, but essentially the same:

>
> サマ（様）の反〔[名語記](https://ja.wikipedia.org/wiki/%E5%90%8D%E8%AA%9E%E8%A8%98)・[大言海](https://kotobank.jp/word/%E5%A4%A7%E8%A8%80%E6%B5%B7-91059)〕

反 should mean 略 ([source](https://kotobank.jp/word/%E5%8F%8D-563548))

