Engineering your own voynich

[MarcoP]

Is that what deterministic means: only one cipher text is possible?

For this it means a given plaintext will always produce the same ciphertext.

Of course, this does not imply that the cipher is reversible. For instance:

A -> Ti
B -> T
C -> i
D -> ii

Both AC and BD are ciphered as Tii. The cipher is deterministic but not reversible.