1. accumulate To amass is to bring together materials that make a mass, a great bulk or quantity. With some occasional exceptions, accumulate is applied to the more gradual, amass to the more rapid gathering Synonyms: amass, accumulate, collect, heap up, hoard up, store up, aggregate, gather, hoard, pile up Antonyms: disperse, divide, portion, spend, waste, dissipate, parcel, scatter, squander