Princeton's WordNet

1. volt, V(noun)

   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

   Synonyms:
   cinque, quint, five, pentad, volt, vanadium, quintet, fin, quintuplet, fivesome, atomic number 23

   Antonyms:
   ordinal

2. vanadium, V, atomic number 23(noun)

   a soft silvery white toxic metallic element used in steel alloys; it occurs in several complex minerals including carnotite and vanadinite

   Synonyms:
   cinque, quint, five, pentad, volt, vanadium, quintet, fin, quintuplet, fivesome, atomic number 23

   Antonyms:
   ordinal

3. five, 5, V, cinque, quint, quintet, fivesome, quintuplet, pentad, fin, Phoebe, Little Phoebe(noun)

   the cardinal number that is the sum of four and one

   Synonyms:
   tail fin, basketball team, louver, cinque, quintet, five, phoebe bird, quin, flipper, pentad, atomic number 23, five-spot, quintette, fin, quint, tailfin, fivesome, quintuple, vanadium, louvre, volt, quintuplet

   Antonyms:
   ordinal

4. V, v(adj)

   the 22nd letter of the Roman alphabet

   Synonyms:
   cinque, quint, five, pentad, volt, vanadium, quintet, fin, quintuplet, fivesome, atomic number 23

   Antonyms:
   ordinal

5. five, 5, v(adj)

   being one more than four

   Synonyms:
   v, five

   Antonyms:
   ordinal