WordNet sense 1 (a soft silvery white toxic metallic element used in steel alloys; it occurs in several complex minerals including carnotite and vanadinite):

vanadium

WordNet sense 2 (the cardinal number that is the sum of four and one):

fin, five, phoebe, quint, quintet, quintuplet, pentad, cinque, fivesome, Little Phoebe

WordNet sense 3 (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):

volt

WordNet sense 4 (the 22nd letter of the Roman alphabet):

letter v

WordNet sense 5 (being or denoting a numerical quantity but not order):

cardinal