If it's 3 non-repeating unordered words, the minimum vocabulary will need to be 256*3 = 768. Realistically you'll need an order of magnitude larger. That's a pretty large vocabulary.

It is a minor point, but 467 words would suffice, as there are 16865705 possibilities to choose 3 elements out of 467. (This is the smallest possible.)

Strictly speaking, yes, if you just view it as unordered sampling without replacement. Although that would squeeze out nearly all of the creative side of things.

That’s not right. 256 * 255 * 254

I suspect you didn't catch gp's meaning: To get to 24 bits of color info, you'd need at least 3 words of 8 bit info each. If you want these to be non-repeating and unordered that makes 256x3=768 unique words.

This isn't correct though.

You need 256 base words, and two substitute words, one of which substitutes for the first repeat, and the other for the second, so 258 words total.

That accounts for the repeating but not the ordering, right?

Oh, by 'unordered' you mean that the three words could be in any order and still mean the same thing?

Okay but that's a strange requirement. A 'big burger house' isn't a 'big house burger', after all.

I had read 'unordered' as 'the collation order of the words has no connection to the ordinal rank of the underlying byte', for some reason

I'm just jumping in where I saw a misunderstanding :) I think that's what they mean by unordered as that makes sense with the numbers (I think).

To some degree I agree, but there are also a lot of cases where different orders aren't distinguishable easily. "Light bright red" and "bright light red" is the best I can come up with quickly but I'm sure you get the idea.