| racing |
the sport of competing with others to be the fastest, esp. in driving a car or riding a horse. |
| racism |
the theory or opinion that a certain race is superior to another or others because of certain inborn characteristics. Racism can underlie the beliefs and actions of both individuals and institutions, as well as those of a society as a whole. [3 definitions] |
| racist |
implying, espousing, or believing in the notion that one race of human beings, typically the race holding the most power and wealth within a society, is superior to another or others. [7 definitions] |
| rack1 |
a frame or structure used to hold or display various items. [9 definitions] |
| racket1 |
loud and irritating noise; din. [3 definitions] |
| racket2 |
a tight net strung on a light, usu. oval frame with a long handle, used to hit the ball in games such as tennis. [3 definitions] |
| racquetball |
a game played by two or four players in a walled court, with small strung rackets for hitting a rubber ball against the walls. |
| radar |
a means of discovering the position, range, and velocity of distant objects by timing the return of high frequency radio waves bounced off their surfaces and analyzing the direction of this return. [2 definitions] |
| radiant |
emitting heat or rays of light. [3 definitions] |
| radiate |
to send forth rays or waves, as of heat or electromagnetic radiation. [8 definitions] |
| radiation |
the emission of particles or waves of energy, as by radioactive material or by electrical circuits or devices. [3 definitions] |
| radiator |
a device, such as that in a car, consisting of tubes through which fluid coolant passes. [3 definitions] |
| radical |
of or relating to roots, origins, or fundamental characteristics; basic. [6 definitions] |
| radii |
a plural form of radius. |
| radio |
the sending of communications by means of electromagnetic waves in the frequency range from ten kilocycles to three hundred thousand megacycles. [9 definitions] |
| radioactive |
emitting energy or subatomic particles as a result of the decay of unstable isotopes. [2 definitions] |
| radioactivity |
the emission or amount of emission of energy or subatomic particles by the nuclei of certain unstable isotopes of elements as they decay. |
| radish |
one of a group of herbs of the cabbage family that have a pungently flavored, crisp, edible root. [2 definitions] |
| radium |
a radioactive chemical element that has eighty-eight protons in each nucleus and that occurs in pure form as a solid metal, used esp. as a radiation source for cancer treatment. (symbol: Ra) |
| radius |
a straight line segment extending from the center to the surface of a sphere or from the center to the circumference of a circle. [7 definitions] |
| radon |
a radioactive chemical element of the inert gas group that has eighty-six protons in each nucleus and that is produced by the radioactive decay of trace amounts of radium in the soil. (symbol: Rn) |