What does R stand for?

Reversal

Difference in directions of surface and upper winds when exceeding 90deg

rolled

Romarco Minerals Inc. (Toronto Stock Exchange [TSX])

Responder

Riser

When referring to drywall, this means to install drywall to the walls and ceilings (with nails and screws), and before taping is performed. Each of the vertical boards closing the spaces between the treads of stairways. Vertical board rising from the back of one tread of a staircase to the front of the next. Reservoir of molten metal from which casting feeds as it shrinks during solidification. A riser is a power line pole that connects an overhead system to an underground system.

Red

Designation applied to an information system, and associated areas, circuits, components, and equipment in which unencrypted national security information is being processed.

Rook

Rarity

Rosy

thermal resistance

Opposition to the flow of heat.