Inter-change, which means to exchange or swap, has several antonyms, including keep, retain, hold, preserve, maintain, and sustain. Instead of inter-changing, one can opt to hold on to or preserve things. For instance, when it comes to ideas or knowledge, one might choose to retain the knowledge they have rather than giving it up by inter-changing it with someone else. One can also maintain or sustain a particular state or condition rather than inter-changing it. The antonyms of inter-change are particularly useful when one wants to keep something intact or maintain it in its current form.