Some letters aren't letters

[ReneZ]

The case of q is even more interesting.


This character appears exclusively at the start of words, and is essentially always followed by o.
Furthermore, it is quite frequent.
Thirdly, the same words without the leading q also occur.
Then, finally, it is not used in label words.

Mapping this character to any plain text letter simply cannot work.

There are other explanations that could make more sense though. Just to give a few examples, (not meaning to be exhaustive, and not suggesting that I firmly believe in either of them):

Linguistically, this could represent a 'stop'. I don't know if there are any known examples where these are written. However, they would make sense in running text and might not be needed in front of single words. Also the next character would have to be a vowel. (Looking forward to Emma's comment on this).

Alternatively, they could be similar to the Greek 'spiritus'. (Vague memories of my one year of classical Greek).
These also only occur with vowels.

Things would look a bit better if one considered qo as a unit rather than q. In this case, one does not even lose a character in the Voynichese alphabet. The strict word-initial usage remains as a major problem though.

What else could this be?

Let's just make a thought experiment. Let's assume that someone took a text, and converted some word-initial consonants as follows:

t ->  ok
s -> qok
r -> ot
n -> qot

I am not saying that this is what was really done, but it would have all sorts of interesting effects.
1) Four plain text characters are mapped to four Voynichese characters. so that balances nicely.
2) This would explain why q is only word-initial, always followed by o
3) It is verbose, and reduces entropy.

Something like this *could* be *part of*  the solution.