bumper

Concise Oxford English Dictionary © 2008 Oxford University Press:
bumper/ˈbʌmpə(r)/

▶noun

• 1 a horizontal bar across the front or back of a motor vehicle to reduce damage in a collision.

• 2 (also bumper race) Horse Racing a flat race for inexperienced horses intended for future steeplechases.

• 3 archaic a generous glass of an alcoholic drink.

▶adjective exceptionally large or successful: a bumper crop.

– phrases
bumper-to-bumper very close together.