The term 'trellis for training fruit trees' can be summarized as the use of an ESPALIER, which is an 8-letter word. An ESPALIER is a framework of latticed wood or metal that is used to support and train fruit trees, such as apple and pear trees, into a desired shape. This technique is used to maximize the amount of sunlight and air circulation that the tree receives, as well as to control the size and shape of the tree.