Source : Webster's Revised Unabridged Dictionary (1913)

Mayonnaise \Ma`yon`naise"\, n. [F.]
   A sauce compounded of raw yolks of eggs beaten up with olive
   oil to the consistency of a sirup, and seasoned with vinegar,
   pepper, salt, etc.; -- used in dressing salads, fish, etc.
   Also, a dish dressed with this sauce.

Source : WordNet®

mayonnaise
     n : egg yolks and oil and vinegar [syn: {mayo}]