The term "most irradiating" has several synonyms, all of which are related to the idea of something being highly impactful or influential. Some potential synonyms for "most irradiating" might include "most enlightening," "most influential," "most powerful," "most striking," or "most inspiring." Each of these terms conveys a similar sense of significant impact. Depending on the context in which the phrase is being used, different synonyms may be more or less appropriate. For example, "most enlightening" might be a good fit for a lecture on a complex topic, while "most inspiring" might be better suited for a motivational speech.