The antonyms for the phrase "losing speed" are various and diverse. One can use words like accelerating, gaining momentum, picking up speed, and increasing velocity as antonyms. These words refer to the opposite of losing speed, which means moving faster and more swiftly. Other relevant antonyms include thriving, growing, improving, progressing, and advancing. These words indicate progress or development, whereas 'losing speed' implies degradation or regression. Therefore, it is crucial to use the appropriate antonym in the right context to convey the intended meaning properly. Understanding antonyms provides a range of vocabulary options that can enhance clarity and precision in communication.