rad
rad — adjective
- radpositive
- raddercomparative
- raddestsuperlative
1. an informal word used to describe something as very impressive, enjoyable, or st
an informal word used to describe something as very impressive, enjoyable, or stylish — a slang term especially popular in the 1980s and 1990s, still used today in casual or ironic contexts.
Tariro thought the vintage leather jacket was totally rad.
totally rad — common intensifier collocation
The skate park has a rad design with ramps and half-pipes painted in neon colors.
Grandma surprised everyone by saying the heavy metal band was 'totally rad'.
Beatriz showed me her dad's old record collection, which looked pretty rad.
Yael said the movie was rad, so I saw it on Friday night.
- lame
slang opposite; describes something disappointing or uncool
文法句型
rad + noun
be + rad
用法筆記
Occasionally used in informal conversation but now carries a dated or ironic tone. Avoid in formal writing. The word is shortened from 'radical', which was used with the same slang meaning.
常見錯誤
rad — noun
1. a unit used in physics and medicine to measure how much ionizing radiation is ta
a unit used in physics and medicine to measure how much ionizing radiation is taken in by a material or living tissue; one rad represents 100 ergs of energy deposited in each gram of the exposed substance.
The technician recorded an exposure of 15 rads during the experiment.
countable: 15 rads
Workers at the nuclear facility must keep their yearly radiation below 5 rads.
A sudden burst of 50 rads can damage bone marrow and requires immediate medical care.
The soil sample from the test site showed an absorbed dose of only 0.3 rads.
Noa checked the dosimeter and noted that the reading had reached 2.5 rads.
- gray (Gy)
the modern SI unit; 1 Gy = 100 rad
文法句型
number + rad(s)
用法筆記
The unit 'rad' has largely been replaced in official contexts by the gray (Gy), where 1 Gy = 100 rad. However, 'rad' is still commonly used in older medical literature and some industrial safety guidelines. The plural form 'rads' is always used after numbers.
常見錯誤
2. a short written form for 'root' in mathematics, used in handwritten calculations
a short written form for 'root' in mathematics, used in handwritten calculations to indicate the square root or another root of a number — for example, 'rad 64' means the square root of 64.
The math teacher asked Hoa to write the rad of 121 on the board.
rad of [number]
Hamza scribbled 'rad 64 = 8' in the margin of his algebra test.
In older textbooks, the square root of 144 is sometimes written simply as rad 144.
Liam solved the problem by writing 'rad 81' instead of drawing the square root symbol.
- root
the full form; 'rad' is simply an abbreviation
- square root
the most common type of root represented by 'rad'
文法句型
rad + number
用法筆記
This informal notation appears mostly in handwritten notes and older textbooks. In modern printed math, the symbol √ is used instead of 'rad'. Not to be confused with the radiation unit 'rad' (which is pronounced the same but has a different meaning).
常見錯誤
❌ Confusing 'rad' (root) with 'rad' (radiation unit). Check the context: math problems use 'rad' for root; physics or medicine texts use 'rad' for radiation dose.
rad — abbreviation
1. a written abbreviation for 'radian' — a standard unit for measuring angles in ma
a written abbreviation for 'radian' — a standard unit for measuring angles in mathematics, where a full circle equals 2π radians.
In geometry, a whole circle measures 2π rad, which is about 360 degrees.
2π rad — standard notation for angle measure
In physics class, Mira converted 30 degrees into 0.524 rad.
The angle of 57.3 degrees is equal to exactly 1 rad.
Ayesha calculated the sine of π/2 rad on her calculator.
文法句型
number + rad
用法筆記
The abbreviation 'rad' is used interchangeably with the spelled-out 'radians' after numbers. Always lowercase. No plural form is needed — '2 rad' is correct (not '2 rads').
常見錯誤
2. a written abbreviation for 'radius' — the distance from the exact center of a ci
a written abbreviation for 'radius' — the distance from the exact center of a circle (or sphere) to any point on its outer edge.
A circle with a rad of 5 cm has an area of about 78.5 square centimeters.
rad of [measurement] — radius in geometry formulas
The truck needs a turning rad of at least 12 meters.
Ayesha calculated the circumference using the rad of the circle.
The architect specified a window with a rad of 8 feet.
- r
the standard symbol in formulas; more common than 'rad' in equations
文法句型
rad of + number
用法筆記
Common in technical drawings, geometry problems, and engineering notes. Usually lowercase. The abbreviation 'r' is even more common than 'rad' for radius in formulas (e.g., A = πr²), but 'rad' appears in written text and labels.
常見錯誤
3. a written abbreviation for 'radix' — the base number of a system of counting, su
a written abbreviation for 'radix' — the base number of a system of counting, such as 10 in the decimal system or 2 in the binary system.
In the decimal counting system that people use every day, the rad is 10.
rad = radix in number-system contexts
Binary has a rad of 2, meaning it uses only the digits 0 and 1.
Computer science's hexadecimal system uses rad 16, with digits 0–9 and A–F.
Liam asked the computer science teacher why the octal system has a rad of 8.
文法句型
rad of + number
用法筆記
Most commonly seen in computer science textbooks and discussions of different number bases. The full term 'radix' is more common in formal writing; 'rad' is an abbreviation used mainly in labels and tables.