Antonyms for the word "over estimations" would include underestimations, undervaluations, downgrades, reductions, and belittlements. These terms refer to the opposite of overestimations, which means to overvalue, exaggerate, or inflate something beyond its actual worth, importance, or capabilities. Underestimations, on the other hand, mean to underestimate or undervalue something, which could result in neglect, failure, or missed opportunities. Downgrades, reductions, and belittlements imply decreasing the value, status, or prestige of something or someone, possibly by criticism, degrading comments, or lack of appreciation. As such, it is important to strike a balance between overestimating and underestimating things, by making informed and realistic evaluations based on evidence, experience, and expertise.