Dictionary

All Word
ray of light Noun a column of light (as from a beacon)
rest energy Noun the energy equivalent to the mass of a particle at rest in an inertial frame of reference
repulsive force Noun the force by which bodies repel one another
resting potential Noun the potential difference between the two sides of the membrane of a nerve cell when the cell is not conducting an impulse
radiation pressure Noun the minute pressure exerted on a surface normal to the direction of propagation of a wave
rocket propulsion Noun reaction propulsion using stored oxygen for combustion
reaction propulsion Noun propulsion that results from the ejection at high velocity of a mass of gas to which the vehicle reacts with an equal and opposite momentum
radiant energy Noun energy that is transmitted in the form of (electromagnetic) radiation
radio wave Noun an electromagnetic wave with a wavelength between 0.5 cm to 30,000 m
radio emission Noun an electromagnetic wave with a wavelength between 0.5 cm to 30,000 m
radio radiation Noun an electromagnetic wave with a wavelength between 0.5 cm to 30,000 m
radio signal Noun a radio wave used to transmit and receive messages
radio spectrum Noun the entire spectrum of electromagnetic frequencies used for communications
radio-frequency spectrum Noun the entire spectrum of electromagnetic frequencies used for communications
rainfall Noun water falling in drops from vapor condensed in the atmosphere
raindrop Noun a drop of rain
rainstorm Noun a storm with rain
reverse lightning Noun atmospheric discharges (lasting 10 msec) bursting from the tops of giant storm clouds in blue cones that widen as they flash upward
red sprites Noun atmospheric electricity (lasting 10 msec) appearing as globular flashes of red (pink to blood-red) light rising to heights of 60 miles (sometimes seen together with elves)
rain shower Noun a brief period of precipitation
radiation field Noun a field that represents the energy lost from the radiator to space
radiopacity Noun opacity to X-rays or other radiation
resistivity Noun a material's opposition to the flow of electric current
radio-opacity Noun opacity to X-rays or other radiation
resolving power Noun the ability of a microscope or telescope to measure the angular separation of images that are close together
red shift Noun a shift in the electromagnetic radiation of a distant object toward longer wavelengths, the red end of the spectrum
redshift Noun (astronomy) a shift in the spectra of very distant galaxies toward longer wavelengths (toward the red end of the spectrum)
roentgen ray Noun electromagnetic radiation of short wavelength produced when high-speed electrons strike a solid target
reactance Noun opposition to the flow of electric current resulting from inductance and capacitance (rather than resistance)
retarding force Noun the phenomenon of resistance to motion through a fluid
rosid dicot family Noun a family of dicotyledonous plants
rosid dicot genus Noun a genus of dicotyledonous plants
resting spore Noun a spore of certain algae or fungi that lies dormant
red cypress pine Noun Australian tree with small flattened scales as leaves and numerous dark brown seed
red spruce Noun medium-sized spruce of eastern North America
red silver fir Noun medium to tall fir of western North America having a conic crown and branches in tiers
red pine Noun pine of eastern North America having long needles in bunches of two and reddish bark
red pine Noun tall New Zealand timber tree
red juniper Noun small juniper found east of Rocky Mountains having a conic crown, brown bark that peels in shreds, and small sharp needles
red cedar Noun fragrant reddish wood of any of various red cedar trees
red cedar Noun tall tree of the Pacific coast of North America having foliage like cypress and cinnamon-red bark
red cedar Noun small juniper found east of Rocky Mountains having a conic crown, brown bark that peels in shreds, and small sharp needles
red cedar Noun large valuable arborvitae of northwestern United States
rimu Noun tall New Zealand timber tree
redwood family Noun coniferous trees
redwood Noun either of two huge coniferous California trees that reach a height of 300 feet
redwood Noun the soft reddish wood of either of two species of sequoia trees
red kauri Noun New Zealand tree with glossy leaves and scaly reddish-brown bark
ray flower Noun small flower with a flat strap-shaped corolla usually occupying the peripheral rings of a composite flower
ray floret Noun small flower with a flat strap-shaped corolla usually occupying the peripheral rings of a composite flower