Expandable, the adjective used to describe something that can be made larger or more comprehensive, has a wide range of synonyms that can be used in its place. In the context of computer hardware, expandable could be replaced with upgradeable, scalable, expandible, or extensible. In the realm of clothing, expandable could be substituted by stretchy, adjustable, or flexible. In terms of data, expandable could be replaced with growable, augmentable, or expandible. In summary, the perfect synonym for expandable would depend on the context where it's being used, but the range of options makes it easy to convey the same meaning in many different ways.