The word "flaggings" refers to weak, droopy or subdued movements. Its antonyms can be strong, vigorous, lively or animated. Some other suitable opposites for this word includes robust, sturdy, forceful or energetic. These antonyms are typically used to express the opposite of tiredness, lethargy or dullness. When a person is not flagging, they are full of vitality, power, and strength. In contrast, when a person is flagging, they are lacking energy and motivation. Therefore, using appropriate antonyms for the word "flaggings" can help convey a different tone and meaning in a sentence.