Greek adjectival nouns (or are they?)

[LCN]

I have a question about a phrase like "to leukon".

First of all etymologically speaking is it correct to read leukon as something like "leuk-on", where on is the participle of einai?

What I mean is does leukon originally read as something like "white-being" but the "on" eventually becomes merely formal? Or am I guessing wrongly here?

The second question is whether you consider it to be more accurate to translate "to leukon" as "white", "whiteness", or "the white thing" (where "thing" is a featureless unity like a monad).

I have a feeling most people treat it like an English adjective, but this seems to me to go against the grain of Greek thinking, where there doesn't seem to be abstract qualities in the modern sense. Not even abstract numbers. (I.e. in Greek there is no "two", but rather "two monads".)

Also if "to leukon" means "white" or "whiteness", (1) what is the "to" doing?, and (2) what is the distinction between to leukon and H leukoths?

[spiphany]

First of all etymologically speaking is it correct to read leukon as something like "leuk-on", where on is the participle of einai?

No. -on is simply the neuter singular nom/acc ending of an adjective or noun of the o-declension. The participle of einai follows the consonant declension.

Also if "to leukon" means "white" or "whiteness", (1) what is the "to" doing?, and (2) what is the distinction between to leukon and H leukoths?

The definite article can be used to make a substantive out of an adjective. This is quite common. In Greek it's not unusual to see the article used with abstract nouns (h eirene, peace; o ploutos, wealth) where English would omit it.
"to leukon" seems to be a standard way to refer to white as a color, or white things in general.
leukoths is far less common, and I think it's a bit more abstract. LSJ gives the meaning of the two words as "white" and "whiteness", respectively.

[LCN]

Thanks, that was helpful.

So if you encountered a phrase contrasting "to leukon" with "to melan", what part of speech would you call that?