Wordnet 3.0
VERB (2)
1. 
 teach new skills; 
- Example: "We must retrain the linguists who cannot find employment"2. 
 train again; 
- Example: "He is retraining to become an IT worker"
WordNet (r) 3.0 (2006):
retrain
    v 1: teach new skills; "We must retrain the linguists who cannot
         find employment"
    2: train again; "He is retraining to become an IT worker"