The distinction between real versus nominal value occurs in many fields.

Engineering

In various subfields of engineering, a nominal value is one which where the "name" for the value is close to, but not the same as, the actual value. Some examples:

• For dimensional lumber in North America, a "two by four" is not 2 inches by 4 inches, but rather 1½ in × 3½ in.
• Mains electricity is nominally 230 V in the European Union, but is allowed to vary ±10%. In North America, the nominal voltage is 120 V, with variance allowed from 114 V to 126 V (±5%).
• NiMH and NiCd rehargable batteries have a nominal voltage of 1.5 V, but actually supply 1.25 V.
• 56 kbit/s modems cannot exceed 53.3 kbits/second.

Other cases involve diameter, speed, and volume.

Sometimes the word "nominal" is also used in engineering contexts as a synonym for "normal".

Economics

Main article: Real versus nominal value (economics)

In economics, "nominal" values are the "face value" of currency over long periods of time (years), whereas "real" values have been corrected for inflation.

External Links

http://www.dallasfed.org/data/basics/nominal.html