The acre is a unit of area in a number of different systems, including the imperial and U.S. customary systems. The most commonly used acres today are the international acre and, in the United States, the survey acre. One international acre is equal to 4,046.856 422 4 m exactly. One U.S. survey acre is equal to ⁄15,499,969 m = 4,046.872 609 874 252 m approximately.
The British thermal unit (BTU or Btu) is a traditional unit of energy equal to about 1.06 kilojoules. It is approximately the amount of energy needed to heat one pound of water one degree Fahrenheit. It is used in the power, steam generation, heating and air conditioning industries. In scientific contexts the BTU has largely been replaced by the SI unit of energy, the joule (J), though it may be used as a measure of agricultural energy production (BTU/kg).
A furlong is a measure of distance in imperial units and U.S. customary units. It is equal to one-eighth of a mile, 220 yards, 660 feet, 201.168 meters, or 10 chains. Five furlongs are approximately 1 kilometer (1.00584 km to be exact).
A gallon is a measure of volume of approximately four litres. Historically it has had many different definitions, but there are three definitions in current use. These are the U.S. liquid gallon (≈ 3.8 L) and the lesser used U.S. dry gallon (≈ 4.4 L) which are in use in the United States, and the Imperial (UK) gallon (≈ 4.5 L) which is in unofficial use within the United Kingdom and Ireland and is in semi-official use within Canada. The gallon, be it the Imperial or U.S.
Horsepower (HP) is the name of several units of measurement of power. The most common definitions equal between 735.5 to 746 watts. The horsepower is not recognized in the International System of Units (SI). The horsepower was originally defined to compare the output of steam engines with the power of draft horses. The unit was widely adopted to measure the output of piston engines, turbines, electric motors, and other machinery. The definition of the unit varied between geographical regions.
An inch is the name of a unit of length in a number of different systems, including Imperial units, and United States customary units. There are 36 inches in a yard and 12 inches in a foot. A corresponding unit of area is the square inch and a corresponding unit of volume is the cubic inch.
A mile is a unit of length in a number of different systems. In contemporary English, a mile most commonly refers to the statute mile of 5,280 feet, the survey mile of 5,280 survey feet (1,609.3472 meters) or the nautical mile of 1,852 meters (6,076.12 ft). The use of statute miles as a unit of measurement is largely confined to the United States and the United Kingdom.
The pound or pound-mass is a unit of mass used in the imperial, United States customary and other systems of measurement. A number of different definitions have been used, the most common today being the international avoirdupois pound of exactly 0.45359237 kilograms. The unit is descended from the Roman libra (hence the abbreviation lb); the name pound is a Germanic adaptation of the Latin phrase libra pondo 'a pound weight'.
In the United Kingdom, the ton is a unit of measure which, when it ceased to be legal for trade in 1985, was defined in British legislation as being a weight or mass [sic] equal to 2,240 pounds (1,016 kg). In the United States and Canada, however, a ton is defined to be 2,000 pounds (907 kg).
A teaspoon, an item of cutlery (in American English, also called flatware), is a small spoon, commonly part of a silverware (usually silver plated, German silver or now, stainless steel) place setting, suitable for stirring and sipping the contents of a cup of tea or coffee. Utilitarian versions are used for measuring. Teaspoons with longer handles, such as iced tea spoons, are commonly used also for ice cream deserts or floats.
Retinoschisis is an eye disease characterized by the abnormal splitting of the retina's neurosensory layers, usually in the outer plexiform layer, resulting in a loss of vision in the corresponding visual field in some rarer forms. More common forms are usually asymptomatic.