The word "quickenings" refers to the act of becoming faster, quick or speeding up. The antonyms for the word would mean the opposite of quickening, i.e. slowing down, reducing speed or decelerating. Examples of antonyms could be slowing, sluggishing, delaying, decelerating, slacking, or reducing speed. There could also be other antonyms that are more specific, such as lethargy, inactivity, stagnation or dullness. Antonyms for the word "quickenings" could be useful in situations where it is necessary to describe activities that require a slower pace or when you want to express a need to reduce stress and hurry.