I. verb — [with obj.] 1. gather together or accumulate (a large amount or number of material or things) over a period of time • he amassed a fortune estimated at close to a million pounds.
2. [no obj.] —
‹archaic› gather together in a crowd or group
• the soldiers were amassing from all parts of Spain.
II. derivatives amasser noun
– origin late 15th cent.: from French amasser or medieval Latin amassare, based on Latin massa ‘lump’ (see mass).