Real Dictionary

steamroller
countable noun: A steamroller is a large, heavy vehicle with wide, solid metal wheels, which is used to make the surface of a road flat. In the past steamrollers were powered by steam.
verb: If you steamroller someone who disagrees with you or opposes you, you defeat them or you force them to do what you want by using your power or by putting a lot of pressure on them.

steamroller in American English
a heavy, originally steam-driven, machine with rollers, used in building and repairing roads
relentlessly overpowering
to bring overwhelming force to bear upon; crush or override as if with a steamroller
to move with overwhelming force, or use steamroller tactics
adjective: suggestive of a steamroller; ruthlessly overpowering
intransitive verb: to proceed with implacable force
noun: a heavy steam-powered vehicle having a roller for crushing, compacting, or leveling materials used for a road or the like
transitive verb: to crush or flatten with a steamroller

steamroller in British English
noun: a steam-powered vehicle with heavy rollers at the front and rear used for compressing road surfaces during road-making