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

viva \vi"va\, interj. it.
   lit., long live; -- an exclamation expressing good will,
   well wishing, etc. -- n. the word viva, or a shout or sound
   made in uttering it.
   webster 1913 suppl.

         a wilder burst of "vivas".               --r. h. davis.
   webster 1913 suppl.

[2] : WordNet (r) 2.0

viva
     n : an examination conducted by word of mouth syn: oral, oral
         exam, oral examination, viva voce
see also:
oral oral exam oral examination viva voce 

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

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