If something is expandable, you can make it bigger. A suitcase or a table can be expandable because extra parts let it hold more. On a computer, a list or a file is expandable when you click and more of it opens; memory is expandable when you are allowed to add more. It is a practical, slightly technical word — you see it on product boxes and in computer talk more than in stories. People also use it as a noun for a thing made to grow, but the adjective is the one you will meet first. Though actually, 'can be made larger' is not the same as 'will grow by itself': an expandable bag still needs someone to unzip the extra bit.