Examples:
He amassed a fortune in the real estate market.
Liz amassed an impressive clientele during the three years she practiced in Chicago.
The U.S. trade deficit has been amassed largely through the purchase of Chinese-made goods.
The movie amassed 1.5 million viewers largely through the passionate support of teenagers.
The barbarian hordes are amassing.
Mappings:
VerbNet: herd-47.5.2
FrameNet: Gathering_up
PropBank: amass.01
WordNet 3.0 Sense Numbers: 1, 2