Respirator

Respiratory pigments (invertebrate)

Respiratory syncytial virus

Respiratory system

Respiratory system disorders

Response

Responses to acute sun exposure in large whales

Rest mass

Restionales

Restoration ecology

Restoration of the American chestnut tree

Restoring regeneration

Restriction enzyme

Resultant of forces

Resveratrol

Retaining wall

Reticular formation

Reticulosa

Retinoid receptor

Retortamonadida

Retrograde motion (astronomy)

Retrovirus

Reverberation

Reverse transcriptase

Reversible express lanes

Revetment

Reynolds number

RFID in transportation and logistics

RGB workflow

Rh incompatibility

Rhabditida

Rhabdocoela

Rhenium

Rheology

Rheostat

Rheumatic fever

Rheumatism

Rhinoceros

Rhinovirus

Rhizocephala

Rhizophorales

Rhizopodea

Rhizosphere

Rhizosphere ecology

Rhizostomeae

Rho-theta system

Rhodium

Rhodochrosite

Rhodonite

Rhodophyceae

Rhombifera

Rhubarb

Rhumb line

Rhynchobdellida

Rhynchocephalia

Rhynchonellida

Rhynchonelliformea

Rhynchosauria

Rhyniophyta

Rhyniopsida

Rhyolite

Riboflavin

Ribonucleic acid (RNA)

Ribosome

Ribosome biogenesis and disease

Ribozyme

Rice

Ricinulei

Rickettsioses

Riemann surface

Riemannian geometry

Rift valley

Rift Valley fever

Rigel

Rigid body

Rigid-body dynamics

Rinderpest

Ring

Ring theory

Ring-opening metathesis polymerization of cycloolefins

Ring-opening polymerization

Ripple voltage

Risk assessment and management

Ritz's combination principle

River

River engineering

River tide

Rivet

RNA interference

RNA mimics of green fluorescent protein

RNA World theory

RNA-Seq transcriptomics

Robotic controlled drilling

Robotic surgery

Robotics

Roche limit

Rock

Rock age determination

Rock burst

Rock cleavage