Cryptocurrency wallet passphrase 10 word? I have a pass phrase with 10 words but can't remember what wallet I used, an every one I have tried is 12. Does anyone know ?
It is possible to have a nine word mnemonic + 1 passphrase word, although it is unusual - you'd probably remember if you specifically chose that combination.

Electrum in BIP39 mode should be able to work with it.

It could also be some random wallet's passphrase system which does not conform to BIP39, in which case electrum will give you a checksum error when you try. If this is the case, you're out of luck unless you can locate the original wallet software.