What do you call a single row of keys on a keyboard if it has more than one (for example on an organ)? Is "claviature" the right word for it (example: "The keyboard of the organ has 4 claviatures.")?
An organ has one or more manuals (and, usually, a pedalboard which the organist plays with his feet).
3 an organ keyboard played with the hands not the feet.
The collection of manuals, together with the stops, is called the console. However, one would normally say "the organ has four manuals" rather than "the organ console has four manuals", because the manuals are always in the console.
An organ console has one or more keyboards (if you mean to be played with the hands or feet) or one or more manuals (if you are referring only to keyboards played by the hands).