The term "levelled off" refers to a state where something has reached a stable point and is no longer increasing or decreasing. Antonyms for this term include "rising," "increasing," "growing," "gaining momentum," "surging," "escalating," "inflating," and "building." On the other hand, antonyms for "levelled off" in the opposite direction include "falling," "decreasing," "dropping," "waning," "dwindling," "diminishing," "declining," "subsiding," and "easing off." Each of these words describes a different trend or pattern and can be used to convey a wide range of ideas related to growth or decline.