Amass/əˈmæs/ Definition 1 of 3Pro Tip 1/3Time Factor Amass implies a gradual process, not instant accumulation. She amassed a decent collection of stamps over the decades. Pro Tip 2/3Large Quantity Use 'amass' when referring to larger quantities, not just a few items. The museum has amassed thousands of artifacts. Pro Tip 3/3Personal Effort Amassing often involves personal effort or skill in collection. He amassed a library of rare books through careful searching.