accelerationEnglishOxford American Thesaurusacceleration noun 1 the car's acceleration is sensational: speeding up, increasing speed, increase in speed, gain in momentum, gathering speed, opening up; technical rate of change of velocity. ▷antonyms deceleration, slowing down. 2 there was some acceleration of the process: hastening, speeding up, quickening, stepping up, advancement, furthering, furtherance, forwarding, promotion, boosting, boost, stimulation, spur, aid, assistance, facilitation, easing, simplification, expedition, precipitation. 3 an acceleration in the divorce rate: increase, rise, advance, leap, surge, escalation, spiralling, worsening.