n A large plant, not exactly defined, but typically over four meters in height, a single trunk which grows in girth with age and branches (which also grow in circumference with age).
n Any plant that is reminiscent of the above but not classified as a tree in the strict botanical sense: for example the banana "tree".
n (graphical user interface) A display or listing of entries or element|elements such that there are primary and secondary entries shown, usually linked by drawn lines or by indenting to the right.