Wordnet 3.0
ADVERB (1)
1. 
 at the beginning; 
- Example: "at first he didn't notice anything strange"[syn: initially, ab initio]
WordNet (r) 3.0 (2006):
ab initio
    adv 1: at the beginning; "at first he didn't notice anything
           strange" [syn: initially, ab initio]