rebound.noun
to bound back; spring back upon impact with something

reservoir.noun
a place where anything is collected and stored

ribose.noun
a monosaccharide. A part of DNA and RNA

ribosomes.noun
ribosomes are responsible for synthesizing-protein-(they build protein chains), and as such, are any of the RNA rich cytoplasmic granules that are sites of protein synthesis. Ribosomes have two sub units with bridges between them. Every time a ribosome builds a protein chain, a series of precisely synchronized-steps must occur at points within the chromosome – an intricate communication system; ribosomes are made of both nucleic acids and proteins. A ribosome is a particle in a cell-(an RNA protein complex) that assembles proteins by organizing-amino acids into particular sequences determined by the nucleotide sequence of RNA

reductio ad absurdum.noun,.plural.reductiones ad absurdum
the proof of a proposition by showing its opposite to be foolish or impossible, or the disproof of a proposition by showing its consequences to be impossible or absurd when it is carried to its logical conclusion

radiation.noun
particle (that's what radiates) radiation is the emission of radiant energy.(a flow of any high speed energetic particles caused by spontaneous.disintegration of atomic-nuclei) as alpha and beta-particles or waves, such as electromagnetic radiation; specifically the process in which energy is sent out from heat, light, alpha and beta particles-(radioactivity). Examples: 1) Energy traveling in the form of electromagnetic waves or photons; 2) a stream of particles, especially alpha or beta particles from a radioactive source such as quarks, or neutrons from a nuclear reactor (an atomic pile in which there is control of the atomic energy produced); the Sun is a large hot nuclear reactor

radiant.adjective
emitting heat or light; consisting of or emitted as radiation (radiant heat); filled with light; bright; glowing; beaming. (after she changed her diet her skin became radiant)
radiant.noun
an object or a point from which light or heat rays are emitted
radiantly.adverb

radiance.also.radiancy.noun
the quality or state of being radiant
Physics.-.the radiant energy emitted per unit time in a specified direction by a unit area of an emitting surface

radiant energy.noun
any form of energy radiating from a source, as electromagnetic waves, sound, heat, light, X-rays, gamma rays, etc.

radioactivity.noun
spontaneous alteration of the nuclei of radioactive atoms, accompanied by the emission of radiation either directly from unstable.atomic.nuclei or as a consequence of a nuclear reaction; 3 types of radioactive radiation.-.alpha particles, beta particles, and gamma rays

radioactive.adjective
of or exhibiting radioactivity
radioactively.adverb

random.noun
impetuous and haphazard movement or course of action; without aim, plan, purpose, or method; as by chance; randomness equates to confusion and disorder, evidencing lack of design, until randomness is examined closely and understood
synonyms.desultory, haphazard, chance

replica.noun
a copy or reproduction of a work of art, especially one made by the original artist; a copy or reproduction, especially one on a scale smaller than the original

replicate.verb
inflected form(s).replicated; replicating
transitive verb senses.duplicate, repeat (replicate a statistical experiment) 
intransitive verb senses.to undergo replication; produce a replica of itself (virus particles replicating in cells) 
replicate.adjective
manifold, repeated 
replicate.noun
one of several identical experiments, procedures, or samples 

retina.noun
the innermost coat of the back part of the eye where the layer of cells sensitive to light are; the image formed by this lens on the retina is carried to the brain by the optic nerve 

ratio.noun
a fixed relation in degree, number, etc. between two similar things; proportion.(a class of 30 with a ratio of 3 girls to 2 boys, would have 18 girls and 12 boys)

recapitulate, recapitulated, recapitulating, recapitulates.verbs
transitive verb use.to repeat in concise form.
Biology.-.to appear to repeat (the evolutionary stages of the species) during the embryonic development of the individual organism
intransitive verb use.to make a summary
recapitulative.or.recapitulatory.adjective

recapitulation.noun
to recapitulate; repetition; repeat; restatement (a summary or concise review); go through it again; repeat during development and growth; the act or process of recapitulating (evolutionary thinking)-ontogeny.recapitulates or repeats phylogeny-– that is, as an embryo develops (ontogeny), it repeats the history of its species.(phylogeny); biogenesis, biosynthesis

reciprocal, reciprocative.adjectives
concerning each of two or more persons or things; given in return; return in kind or degree; mutual
reciprocality, reciprocation, reciprocator.nouns
reciprocate.transitive verb
to give and get; to cause to move alternately back and forth; interchange position 
reciprocality.noun
reciprocally.adverb

reciprocity.noun
mutual action; interchange; mutual exchange; for every action there is a reaction 

refraction.noun
when a light wave moves from one medium to another (as from air to glass), it moves with a different speed in the second medium; this change in speed causes its direction to change; amount of refraction depends on how dense the media is and other factors having to do with angle, speed, etc. 

refractory.adjective
resistant to heat; hard to melt; materials that can withstand high temperatures, like the bricks on the inside of blast furnaces

repercussion.noun
an often indirect effect, influence, or result that is produced by an event or action; impact; a recoil, rebounding, or reciprocal motion after impact; reflection
repercussive.adjective

reproach, reproached, reproaching, reproaches.transitive verbs
to express disapproval of, criticism of, or disappointment in someone; admonish; to bring shame upon; disgrace
reproach.noun
blame; rebuke; one that causes rebuke or blame; disgrace; shame
beyond reproach.idiom
so good as to preclude any possibility of criticism
reproachable.adjective
reproachableness, reproacher.nouns
reproachably.adverb
reproachful.adjective
expressing reproach or blame
reproachfully.adverb
reproachfulness.noun

resplendent.adjective
splendid or dazzling in appearance; brilliant
resplendence.or.resplendency.noun
resplendently.adverb

resin.noun
any of numerous clear to translucent yellow or brown, solid or semisolid, viscous substances of plant origin, such as copal, rosin, and amber, used principally in lacquers, varnishes, inks, adhesives, synthetic plastics, and pharmaceuticals; any of numerous physically similar polymerized synthetics or chemically modified natural resins including thermoplastic materials such as polyvinyl, polystyrene, and polyethylene and thermosetting materials such as polyesters, epoxies, and silicones that are used with fillers, stabilizers, pigments, and other components to form plastics
resin, resined, resining, resines.transitive verbs
to treat or rub with resin
resinous.adjective