Accumulate means to gather or collect items or things over time. There are several words that can be used as synonyms for accumulate. One common synonym for accumulate is amass, which refers to the act of collecting or gathering things together. Another synonym is accumulate, which refers to the steady increase in the quantity or amount of something. A third synonym is accrue which refers to the gradual buildup of something over time. Other synonyms for accumulate include gather, stockpile, collect, hoard, and assemble. All of these words convey the idea of something being slowly but steadily collected over time.