When we talk about being deficient, we refer to something that is lacking or insufficient. However, there are several antonyms that convey the opposite meaning. For instance, a word that is the opposite of deficient is adequate, which means sufficient or satisfactory. Another antonym for deficient is plentiful, which means a large amount or abundant. Ample is also a suitable antonym meaning more than enough or sufficient. Competent is another antonym for deficient meaning efficient or capable. Finally, words such as abundant and overflowing are also antonyms for deficient, indicating that something is plentiful and more than sufficient. In conclusion, the antonyms for deficient represent a state of abundance, sufficiency, competence, and capability.