 nail

an old English unit of length equal to 1/20 ell, also used for measuring cloth
like the ell; originally, it represented the length of the last two joints
(including the fingernail) of the middle finger. The nail is equivalent to 1/16
yard, 1/4 span, 2.25 inches, or exactly 5.715 centimeters.
 nano (n)

a metric prefix meaning 10^{9}, or one billionth. The prefix comes
from the Greek word nanos, dwarf.
 nanometer (nm)

a metric unit of distance equal to 10^{9} meter. The nanometer
replaced the millimicron in 1951. One nanometer equals 0.001 micrometer
or 10 angstroms.
 nanosecond (ns)

a unit of time equal to 10^{9} second.
 nautical mile

a unit of distance used primarily at sea and in aviation. The nautical mile is
defined to be the average distance on the Earth's surface represented by one
minute of latitude. Because the Earth is not a perfect sphere, it is not easy
to measure the length of the nautical mile in terms of the statute mile used on
land. For many years the British set the nautical mile at 6080 feet (1853.18
meters), exactly 800 feet longer than a statute mile; this unit was called the
Admiralty mile. The international nautical mile is
exactly 1852 meters or 6076.115 49 feet, about 1.1508 statute miles. It is
designed to equal 1/60 degree,although actual degrees of latitude vary from
about 59.7 to 60.3 nautical miles.
 nest

an old English unit of quantity equal to 3.
net ton

(1) another name for the U.S. or short ton of 2000 pounds.

(2) another name for the register ton, a unit of volume equal to 100
cubic feet in describing the cargocarrying capacity of a ship as opposed to
the entire interior volume.
 newton (N)

the SI unit of force. A force of one newton will accelerate a mass of one
kilogram at the rate of one meter per second per second. The corresponding unit
in the CGS system is the dyne (10^{5} dynes is one newton). The
newton is also equal to about 0.101 972 kilograms of force (kgf) or kiloponds
(kp). The newton is named for Isaac Newton (16421727), the British
mathematician, physicist, and natural philosopher. He was the first person to
understand clearly the relationship between force (F), mass (m),
and acceleration (a) expressed by the formula F = ma.
 ngarn

a unit of land area in Thailand. The ngarn equals 1/4 rai, 100 talangwah (tw),
or 400 square meters (478.396 square yards).
 noeud

French word for the knot (1.852 km/h), the traditional unit of velocity
at sea. It is still used officially in France.
 noggin

a traditional unit of liquid volume in Ireland. The noggin is often taken
to equal 1/4 pint or to be 1/2 pint.
 nook

a traditional unit of land area in northern England. Originally the nook was
1/2 virgate (a virgate, often called a yardland in the north, was about
30 acres in southern England but tended to be closer to 40 acres in the north).
A nook of land is 20 acres or about 8.094 hectares.
 normal cubic meter (Nm^{3})

a unit of mass for gases equal to the mass of 1 cubic meter (35.3147 ft^{3})
at a pressure of 1 atmosphere and at a standard temperature, often 0 °C (32
°F); or term standard cubic meter is also called at 20 °C
(68 °F).
 note

a unit of relative time in music, also called a whole note, equal to 1/2
breve.
 nox

a unit of (low) illumination equal to 0.001 lux. "Nox" is the Latin word
for "night."
