Wordnet 3.0
NOUN (2)
1. 
 a swelling rush of anything; 
- Example: "he rose on the springtide of prosperity"2. 
 a greater than average tide occurring during the new and full moons; 
The Collaborative International Dictionary of English v.0.48:
Springtide \Spring"tide`\ (-t[imac]d`), n.
   The time of spring; springtime. --Thomson.
   [1913 Webster]
WordNet (r) 3.0 (2006):
springtide
    n 1: a swelling rush of anything; "he rose on the springtide of
         prosperity"
    2: a greater than average tide occurring during the new and full
       moons [ant: neap, neap tide]