The term "more sericeous" can be replaced with a number of synonyms, depending on the context in which it is being used. For instance, if one is referring to a more serious tone or mood, they may use synonyms such as solemn, grave, somber, or earnest. Alternatively, if one is referring to a more serious situation or problem, they may use synonyms such as critical, urgent, or pressing. Similarly, if one is referring to a more serious attitude or outlook, they may use synonyms such as sober, mature, or responsible. Overall, the particular synonym used will depend on the specific context and meaning of "more sericeous" in a given situation.