Readily Achievable: Easily accomplishable and able to be carried out without much difficulty or expense. In determining whether an action is readily achievable, factors to be considered include nature and cost of the action, overall financial resources and the effect on expenses and resources, legitimate safety requirements, impact on the operation of a site, and, if applicable, overall financial resources, size, and type of operation of any parent corporation or entity.

Receptive language: The ability to understand spoken and written communication as well as gestures.

Reciprocal motion: The alternate movements of arms and legs.

Reflex: An involuntary movement in response to stimulation such as touch, pressure, or joint movement.

Reinforcement: Providing a pleasant consequence (positive reinforcement) or removing an unpleasant consequence
(negative reinforcement) after a behavior in order to increase or maintain that behavior.

Related services: Any service that enables a child to benefit from his or her educational program.

Repetitive Motion: The sequential continuation of a movement.

Respiration: Breathing.

Respite care: Skilled care and supervision of an adult or child with disabilities that can be provided in the family's home or the home of a care-provider. Respite care may be available for several hours per week or for overnight stays and is often publicly funded.

Retina: The lining of the back portion of the eye which receives visual images.
Retinopathy of Prematurity (R.O.P.): A condition in which high concentrations of oxygen received while a baby is on a respirator damages capillaries in the eye, leading to myopia or a detached retina.

Retraction: Drawing back a part of the body.

Rh Incompatibility: A blood condition in which antibodies in pregnant woman's blood can attack fetal blood cells, impairing the fetus's supply of oxygen.*

Rigidity: Extremely high muscle tone in any position, combined with very limited movements.

Rood Method: A technique used by some Ots and PTs to desensitize overly sensitive areas of the body through brushing, the application of heat or cold, and other methods.

Rooting: A newborn reflex in which babies turn their mouths toward the breast or bottle to feed.

Rubella: Also known as German measles, rubella is a viral infection that can damage the nervous system in the developing fetus.