Wordnet 3.0
NOUN (1)
1. 
 an early symptom that a disease is developing or that an attack is about to occur; 
[syn: prodrome, prodroma]
WordNet (r) 3.0 (2006):
prodroma
    n 1: an early symptom that a disease is developing or that an
         attack is about to occur [syn: prodrome, prodroma]