What does R stand for?

Restricted Area

A specified area on land or water designated by an appropriate authority within which access or navigation is restricted in accordance with certain specified conditions. A deck, space, area, etc., not permitted to be entered for safety reasons.

Sticking Tongue Out

The Resurrection

Pyrimidine

Pyrimidine is an aromatic heterocyclic organic compound similar to pyridine. One of the three diazines (six-membered heterocyclics with two nitrogen atoms in the ring), it has the nitrogens at positions 1 and 3 in the ring. The other diazines are pyrazine (nitrogens 1 and 4) and pyridazine (nitrogens 1 and 2). In nucleic acids, three types of nucleobases are pyrimidine derivatives: cytosine (C), thymine (T), and uracil (U).

Range

The difference between the highest and lowest values of a measurable attribute of the output of a process. An area between two limits within which a quantity is measured, stated in terms of a lower and upper limits. The categorization of an attribute into different segments. The set of values that a quantity or function may take.

Radial

Line from a VOR or NDB. For example, the 180 radial from a VOR represents a line south of that VOR. In a direction directly outward from the center of a circle or sphere or from the axis of a cylinder. The spokes of a wheel, for example, are radial. A magnetic bearing extending from a very high frequency omni-range and/or tactical air navigation station.

Radical

An atom or group of atoms that contains one or more unpaired electrons (usually very reactive species)

Rubber

Steel block with rounded face and wooden handle Used for rubbing down seams in canvas after they have been sewn. 'Rubbing Piece'.

Recognition

Reduction

A 'leading back' Correction of an apparent position or value, to give a true position, or value. In general, the transformation of data from a "raw" form to some useable form.