The word "aiyo" is commonly used in India and other parts of South Asia to express surprise, dismay, or frustration. While there is no exact synonym for "aiyo," there are several alternatives that convey similar meanings. For instance, one could say "oof" or "oh dear" to express surprise or dismay. Alternatively, "geez" or "cripes" can be used to convey annoyance or frustration. Another option could be "alas" or "oh no," which can be used to express disappointment or sorrow. Ultimately, the choice of synonym will depend on the specific context and tone of the conversation.