What term describes excessively flattering or ingratiating behavior?

The term that describes excessively flattering or ingratiating behavior is "officious." This word generally refers to someone who is eager to offer unnecessary help or advice, often in a way that is intrusive or overly assertive. When applied in the context of flattery, it conveys the idea of someone who is excessively helpful or accommodating to curry favor, often coming off as insincere or self-serving.

In contrast, the other choices do not relate to flattery. "Luculent" means clear or easily understood, particularly in terms of speech or expression; it does not have connotations of flattery. "Lubricious" typically describes something that is sexually suggestive or lewd, rather than ingratiating. "Maculate" refers to something that is spotted or stained, which is unrelated to behavior or flattery. Thus, "officious" is the correct answer as it aptly captures the essence of insincere or excessive flattery.