Web infotk.com

a large traditional unit of land area in Mexico and the southwestern U.S.  5 square leguas or 125 million square varas. Based on Texas definition of the vara, would be about 8960 hectares or 22 140 acres (34.59 square miles). Using the shorter Mexican vara, it would be about 8778 hectares or 21 690 acres.
a German word for one half; often used as a unit of volume for beer and other liquids equal to 1/2 maß (1/2 liter).
a unit of proportion equal to 1/2.
half step
a unit used in music to describe the ratio in frequency between notes. Equal to 1/12 octave, the half step measures the difference between adjacent notes in the standard 12-tone scale, as on a piano keyboard.
a traditional unit of distance. One hand equals 4 inches, 1/3 foot, or 10.16 centimeters.
a traditional measure of length for yarn. The length of yarn in a hank varies with the market and the material. In the U.S., a hank of woolen yarn is generally 1600 yards (1463 meters). In retail trade, a hank is often equal to 6 or 7 skeins of varying size.
a measure of the hardness of a metal or mineral. Hardness is a property easy to appreciate but difficult to quantify and measure.
a unit of quantity for livestock, equal to one animal. No 's' is added for the plural: e.g. "36 head" of cattle.
heaped bushel
a traditional unit of volume in the United States, the heaped bushel is just what its name implies: the volume of a bushel container filled to overflowing. Officially, the heaped bushel was supposed to equal 1.278 regular, or "struck" bushels, frequently interpreted as 1.25 bushels, which is equal to exactly 5 pecks, 2688.025 cubic inches, 1.5556 cubic feet, or 44.049 liters.
heat index
a measure of the combined effect of heat and humidity on the human body.
heating degree day (HDD)
see degree day.
heat unit
an alternate name, coined by Americans, for the British thermal unit (Btu). This is not the same as the Celsius heat unit (Chu).  
hect- or hecto- (h-)
a metric prefix denoting 100, coined from the Greek word hekaton for one hundred.
hectare (ha)
the customary metric unit of land area, equal to 100 ares. One hectare is a square hectometer, that is, the area of a square 100 meters on each side: exactly 10 000 square meters or approximately 107 639.1 square feet, 11 959.9 square yards, or 2.471 054 acres.
hectare meter(ha·m)
a unit of volume used to measure the capacity of reservoirs, equal to the volume of water one meter deep covering one hectare. One hectare meter equals exactly 10 000 cubic meters or about 8.1071 acre feet.
hectobar (hbar)
a very common metric unit of pressure equal to 100 bars, 10 megapascals (MPa), or 1 dekanewton per square millimeter (daN/mm2). This is approximately 1450.38 pounds per square inch (lbf/in2 or psi) or 208 855 pounds (104.43 U.S. tons) per square foot.
hectogram (hg)
a common metric unit of mass, equal to 100 grams or about 3.5274 ounces.
hectoliter (hL or hl)
a common metric unit of volume. The hectoliter equals 100 liters, 0.1 cubic meter, 26.417 U.S. liquid gallons, 21.999 British imperial gallons, or 3.5315 cubic feet.
hectometer (hm)
a metric unit of distance equal to 100 meters, 328.084 feet, or 109.361 yards.
hectopascal (hPa)
a metric unit of pressure equal to 100 pascals or 0.1 kilopascal (kPa). The hectopascal, used almost entirely in measurements of air pressure, is identical to the millibar (mb). The SI unit for air pressure is the kilopascal.
a traditional measure of length for linen and woolen yarn, equal to 2 cuts or 1/6 hank (see above). This is equivalent to 80 yards (73.152 meters).
helek (hl)
a traditional Hebrew unit of time equal to 1/1080 hour, 1/18 minute or 10/3 seconds. The plural is halakim. Halakim are used in formulas establishing the instant of new moon, which marks the start of the month in the Jewish calendar.
a Roman unit of liquid volume, equal to 1/2 sextarius or about 265.6 milliliters (0.561 U.S. pint or 0.467 British Imperial pint).
a traditional unit of solid angle equal to 1/2 sphere, 2pi steradians, or about 20 626.48 square degrees.
a unit of quantity equal to 7.
hertz (Hz)
the SI unit of frequency, equal to one cycle per second. The hertz is used to measure the rates of events that happen periodically in a fixed and definite cycle. Multiples of the hertz are common: the frequencies of radio and television waves are measured in kilohertz (kHz), megahertz (MHz), or even gigahertz (GHz), and the frequencies of light waves in terahertz (THz). The unit is named for the German physicist Heinrich Rudolf Hertz (1857-1894), who proved in 1887 that energy is transmitted through a vacuum by electromagnetic waves.
a unit of quantity equal to 6.
a unit of information equal to 4 bits or 1/2 byte. A string of 4 bits has 16 possible states (0-15) and is usually represented as a single base-16, or hexadecimal, digit (in the hexadecimal system the letters A through F are used to represent the numbers 10 through 15, respectively). A hexit of data is also known as a nibble or a quadbit.
an ancient Hebrew unit of liquid capacity, mentioned in the Bible. The unit varied in size over time, but typically it was around 3.7 liters, a little smaller than the U.S. gallon.
one of two Hungarian units of land area. The traditional magyar hold or Hungarian acre is equal to 1200 square öl (fathoms) or about 0.4314 hectare (1.066 acres).
a historic unit of area in the United States, equal to 160 acres (64.75 hectares). A homestead equals 1/4 square mile, or 1/4 section in U.S. government terminology.
slang for the horsepower.
horsepower (hp)
a unit of power representing the power exerted by a horse in pulling. The horsepower was defined by James Watt (1736-1819), the inventor of the steam engine, who determined after careful measurements that a horse is typically capable of a power rate of 550 foot-pounds per second. The SI unit of power is named for Watt, and one horsepower is equal to approximately 745.6999 watts.
horsepower hour (hp hr)
a unit of work or energy equal to the work done at the rate of 1 horsepower for 1 hour. The horsepower hour equals 1 980 000 foot pounds or approximately 2.685 megajoules, 2545 Btu, 641.1 (large) Calories, or 745.7 watt hours.
hour (h or hr)
a traditional unit of time, equal to 60 minutes, or 3600 seconds, or 1/24 day. Originally an hour was 1/12 of the time between sunrise and sunset, so summer hours were longer than winter hours. Later, when people wanted to express times at night, it was natural to divide the night into 12 hours as well, making 24 hours in the day. The word comes from an ancient Greek word hora which originally meant a season, especially a religious season, and hence a "defined" period of time.

a unit of angular measure used in astronomy, equal to 1/24 circle or 15°. Latitude is measured in degrees from the equator to the poles, just as it is on the surface of the earth. Longitude is replaced by right ascension, measured in hours from the longitude, traditionally known as the First Point of Aries, at which the Sun crosses the equator on its northward journey in the spring.
a traditional Chinese unit of liquid volume. The hu contains about 51.77 liters, 13.676 U.S. gallons, or 11.389 British imperial gallons.
a numerical measure of color; see color units.
hundredweight (Cwt or cwt)
a traditional unit of weight equal to 1/20 ton.


Copyright  2006 by Infotk.com