Wikipedia
The claviorgan (also known as the claviorganum,claviorgano, clavecin organisee) is a combination of a stringed instrument (usually a keyboard instrument) and an organ. Its origin is uncertain but its history can be traced back to the fifteenth century.
A number of "virgynalls with regals" are mentioned in the inventories of Henry VIII in 1542/3 and 1547 and Wilson Barry cites references to the claviorganum in England dating back to the 1530s. The term claviorgan in its strictest sense refers to the combination of a harpsichord (or other harpsichord type instrument) and an organ, although later could also be used to refer to a combination of a piano and organ. Michael Praetorius describes the claviorgan in his Syntagma Musicum of 1619 as
" ... a clavicymbal, or some other symphony, in which a number of pipes is combined with the strings. Externally it looks exactly like a clavicymbal or symphony, apart from the bellows, which are sometimes set at the rear and sometimes placed inside the body"