Even when casually looking at the pages of the VM, it’s obvious that the words aren’t generated at random: There are many repeating letter sequences, several letters or “syllables are always word-initial (“qo”, for example) or word-terminal (“dy”), some letters are always follwed by certain others etc.
Here’s my attempt to write down a “grammar” for the VM. It is valid only for the “Currier B” part of the manuscript, and will not explain all, but the most frequent of words:
The following diagram shows a grammar for “legal” (ie existing) words in the Voynich Manuscript.
As a source I’ve used the most frequent words in the recipes section (Currier hand “B”) and manually developed a grammar which would be as simple as possible while covering most of the words.
To create a word, start at the “Space” symbol and follow the arrows until you arrive at “Space” again.
The following rules apply:
1) Only if not preceded by “q” in the word,
2) Only if no start group has been used,
3) Up to four of these characters
(I’m not fully statisfied with the “chke” situation, but it’s difficult to assess due to the similarity of the letters.)