The Collaborative International Dictionary of English v.0.48:

Custodial \Cus*to"di*al\ (k?s-t?"d?-al), a. [Cf. F. custodial,
   fr. L. custodia. See Custody.]
   Relating to custody or guardianship.
   [1913 Webster]

WordNet (r) 3.0 (2006):

custodial
    adj 1: providing protective supervision; watching over or
           safeguarding; "daycare that is educational and not just
           custodial"; "a guardian angel"; "tutelary gods" [syn:
           custodial, tutelary, tutelar]

Moby Thesaurus II by Grady Ward, 1.0:

37 Moby Thesaurus words for "custodial":
   Argus-eyed, all ears, all eyes, aux aguets, covering, defensive,
   eagle-eyed, fostering, guarded, guardian, guarding, hawk-eyed,
   immunizing, keen-eyed, lidless, observant, on guard,
   on the lookout, on the watch, open-eyed, parental, preventive,
   prophylactic, protecting, protective, prudent, safeguarding,
   screening, sharp-eyed, sheltering, shielding, sleepless, tutelary,
   vigilant, wary, watchful, with open eyes