[1] : The Collaborative International Dictionary of English v.0.48

viva voce \vi"va vo"ce\ vimac"v.a v=o"s-e. l.
   by word of mouth; orally.
   1913 webster

[2] : WordNet (r) 2.0

viva voce
     n : an examination conducted by word of mouth syn: oral, oral
         exam, oral examination, viva
     adv : orally; "i heard it viva voce" syn: by word of mouth
see also:
oral oral exam oral examination viva by word of mouth 

[3] : Moby Thesaurus II by Grady Ward, 1.0

24 moby thesaurus words for "viva voce":
   articulate, articulated, enunciated, lingual, linguistic,
   nuncupative, oral, orally, parol, pronounced, said, sonant,
   sounded, speech, spoken, unwritten, uttered, verbal, verbally,
   vocal, vocalized, vocally, voiced, voiceful

[4] : Bouvier's Law Dictionary, Revised 6th Ed (1856)

viva voce. living voice; verbally. it is said a witness delivers his 
evidence viva voce, when he does so in open court; the term is opposed to 
deposition. it is sometimes opposed to ballot; as, the people vote by 
ballot, but their representatives in the legislature, vote viva voce. 

Viva Voce >> V Words
Viva Voce, definition of term: Viva Voce
viva+voce_pag1.html

Viva >> V Words
Viva, definition of term: Viva
viva_pag1.html

Sotto Voce >> S Words
Sotto Voce, definition of term: Sotto Voce
sotto+voce_pag1.html