Wordnet 3.0
NOUN (1)
1. 
 the position of custodian; 
The Collaborative International Dictionary of English v.0.48:
Custodianship \Cus*to"di*an*ship\, n.
   Office or duty of a custodian.
   [1913 Webster]
WordNet (r) 3.0 (2006):
custodianship
    n 1: the position of custodian