More ungrudging, meaning being more generous or giving without hesitation, can have several antonyms. The opposite of ungrudging can be grudging, which means being reluctant or unwilling to give. Another antonym can be selfish or stingy, which implies a lack of generosity or a reluctance to share with others. Additionally, the opposite of ungrudging can be envious, which can mean a feeling of resentment towards others' success, achievements or wealth. Therefore, while ungrudging indicates a generous behavior, the antonyms such as grudging, selfish, stingy, and envious signify negative traits that have an adverse impact on one's relationships and reputation.