Princeton's WordNet

1. second, sec, s(noun)

   1/60 of a minute; the basic unit of time adopted under the Systeme International d'Unites

   Synonyms:
   endorsement, second, instant, sulfur, sulphur, secondment, s, second base, second gear, sec, secant, moment, siemens, indorsement, due south, reciprocal ohm, mho, south, mo, irregular, southward, entropy, randomness, atomic number 16, bit, arcsecond, minute

2. sulfur, S, sulphur, atomic number 16(noun)

   an abundant tasteless odorless multivalent nonmetallic element; best known in yellow crystals; occurs in many sulphide and sulphate minerals and even in native form (especially in volcanic regions)

   Synonyms:
   due south, entropy, southward, sec, reciprocal ohm, south, second, siemens, sulfur, atomic number 16, randomness, sulphur, mho

3. south, due south, southward, S(noun)

   the cardinal compass point that is at 180 degrees

   Synonyms:
   due south, entropy, southward, sec, reciprocal ohm, south, second, siemens, sulfur, atomic number 16, randomness, sulphur, mho

4. mho, siemens, reciprocal ohm, S(noun)

   a unit of conductance equal to the reciprocal of an ohm

   Synonyms:
   due south, entropy, southward, sec, reciprocal ohm, south, second, siemens, sulfur, atomic number 16, randomness, sulphur, mho

5. S, s(noun)

   the 19th letter of the Roman alphabet

   Synonyms:
   due south, entropy, southward, sec, reciprocal ohm, south, second, siemens, sulfur, atomic number 16, randomness, sulphur, mho

6. randomness, entropy, S(noun)

   (thermodynamics) a thermodynamic quantity representing the amount of energy in a system that is no longer available for doing mechanical work

   Synonyms:
   south, entropy, southward, due south, second, stochasticity, sulfur, sec, selective information, sulphur, siemens, reciprocal ohm, information, noise, haphazardness, randomness, mho, atomic number 16