The word "advise against" refers to the act of recommending not to do something. Its antonyms include "suggest," "recommend," "endorse," "approve," "encourage," "advocate," "support," "commend," and "cheer on." These words all promote the idea of doing something, rather than discouraging it. For instance, if you advise against climbing a tree, you suggest not climbing the tree, but if you recommend climbing a mountain, you encourage it. In essence, antonyms of "advise against" focus on promoting or recommending an action, rather than warning against it.