The word "yo-yoed" refers to a repetitive up and down movement or fluctuation. Some possible antonyms for "yo-yoed" include stability, consistency, steadiness, uniformity, or predictability. These words suggest a state or trend that is reliable, constant, regular, or stationary, rather than erratic or unpredictable. For example, a company's profits may have yo-yoed over the years, but if they are now enjoying a stable growth, we could say their revenue has steadied. Similarly, a person's weight may have yo-yoed due to dieting, but if they have maintained a healthy weight for a long time, we could say their body mass has stabilized.