roller
bird
any of about 12 species of Old World birds constituting the family Coraciidae (order Coraciiformes), named for the dives and somersaults they perform during the display flights in courtship. The family is sometimes considered to include the ground rollers (ground roller) and cuckoo rollers. Rollers inhabit warm regions from Europe and Africa to Australia.
Ranging in length from 25 to 32 cm (10 to 13 inches), rollers look like stocky, short-legged jays and are predominately blue or violet in colour. They gather in noisy flocks to feed on locusts, flying ants, and lizards. Most nest in tree holes; some burrow in termite nests.The 30-centimetre- (12-inch-) long common roller (Coracias garrulus), found from southern Europe to western Asia, has vivid blue wings with black borders. See also cuckoo roller; ground roller.
farm machine
farm implement used to break up lumps left by harrows and to compact the soil, eliminating large air spaces. The plain roller is often used to compact grassland damaged by winter heaving. Corrugated rollers, single or tandem, crush clods and firm the soil after plowing. A type usually called a roller-packer or land presser has heavy, wedge-shaped wheels about 3 feet (1 m) in diameter and is used in dry seasons to compress the soil after plowing.