Ultrabasic Rock: An igneous rock with a very low silica content and rich in minerals such as hypersthene, augite and olivine. These rocks are also known as ultramafic rocks.
Acidic Rock: An igneous rock that has a relatively high silica content. Examples are granite and rhyolite. Also see entries for basic, intermediate and ultrabasic rocks.
Intermediate Rock: An igneous rock that has an intermediate silica content. Examples are syenite and diorite. Also see entries for acidic, basic and ultrabasic rocks.
Basic Rock: An igneous rock that has a relatively low silica content. Examples are gabbro and basalt. Also see entries for acidic, intermediate and ultrabasic rocks.
Rocker Arm: A centrally pivoted lever that transmits the motion of the camshaft to open and close the valves.
Rocker: A broad-ended tool with a sharp-toothed curved base which is used to ground a mezzotint plate. It is so called because it is applied with a rocking motion.
Rocked: Big hit
Rockered Blades: Used by professional ice hockey skaters; the gentle curve in a very sharp blade of an ice skate produced by rounding the toe and heel of the blade to make it easier for hockey players to tur . . . View Full Definition
Rocker Step: An offensive move consisting of a jab step followed by a step backward; the player can either shoot or drive, depending on the movement of the defender.
Rock Flour: A glacial sediment of extremely fine (silt-and clay-size) ground rock formed by abrasion of rocks at the base of the glacier.