a unit of potential equal to the potential difference between two points on a conductor carrying a current of 1 ampere when the power dissipated between the two points is 1 watt; equivalent to the potential difference across a resistance of 1 ohm when 1 ampere of current flows through it
The two letters were formerly used indiscriminately, and till a comparatively recent date words containing them were often classed together in dictionaries and other books of reference (see U)
The Latin derives it from it from a form (V) of the Greek vowel Υ (see Y), this Greek letter being either from the same Semitic letter as the digamma F (see F), or else added by the Greeks to the alphabet which they took from the Semitic