Nice Nelly is a term typically associated with someone who is overly nice, meek, or excessively polite. The antonyms of Nice Nelly would include words such as harsh, aggressive, unfriendly, impolite, and tough. A person who is a total opposite to Nice Nelly would be someone who is hard-nosed, uncompromising, and assertive. The antonyms of Nice Nelly relate to personalities that are more direct, honest, and upfront in their interactions with others. In certain situations, these personality traits can be beneficial, such as in negotiations where the ability to stand firm can lead to advantageous outcomes. However, individuals that take an aggressive approach excessively could create conflict and negatively impact relationships.