The antonyms for "be prolific" are "be unproductive," "be sterile," "stagnate," and "fail to produce." These terms are employed to explain a lack of creativity or initiative in producing new ideas, work, or content. Being unproductive implies a lack of inspiration or motivation to undertake anything productive or fruitful. Sterility denotes infertility or unproductiveness in generating ideas or thoughts. Stagnation means a lack of growth or development in one's work or ideas. The phrase "fail to produce" implies an inability to generate anything of value or use. Overall, the antonyms for "be prolific" imply a lack of creativity, productivity, or progress in one's endeavors.