The term 'orchard unit' can be broken down into two crossword solutions: BUSHEL (6 letters) and tree (4 letters). A BUSHEL is a unit of measurement for dry goods, such as fruits and vegetables, which is equivalent to 8 gallons. A tree is a woody perennial plant that typically has a single stem or trunk growing to a considerable height and bearing lateral branches. In the context of an orchard, a BUSHEL is a unit of measurement for the amount of fruit harvested from a single tree.