To claim something means to:

To claim something means to assert it as truth. This implies a strong declaration or statement made by an individual regarding a particular fact, idea, or belief. When someone makes a claim, they are often putting forth information that they believe to be correct or valid, which can include opinions or evidence-based assertions.

In contrast, denouncing something involves publicly declaring it to be wrong or evil, which does not align with the act of claiming. Ignoring something signifies a lack of attention or refusal to acknowledge it, thus not engaging in any assertion. Redefining something would mean changing the established definition or understanding of it, which is different from merely asserting a truth. Thus, the act of claiming inherently involves a communicative assertion rather than any of these other actions.