The Collaborative International Dictionary of English v.0.48:

Secretive \Se*cret"ive\, a.
   Tending to secrete, or to keep secret or private; as, a
   secretive disposition.
   [1913 Webster]

WordNet (r) 3.0 (2006):

secretive
    adj 1: inclined to secrecy or reticence about divulging
           information; "although they knew her whereabouts her
           friends kept close about it" [syn: close,
           closelipped, closemouthed, secretive,
           tightlipped]