adjective.
Not disposed to be forthcoming or communicative; uncommunicative.
The Century Dictionary and Cyclopedia
Not disposed to impart to others, as information or ideas; reserved; uncommunicative.
the GNU version of the Collaborative International Dictionary of English
adjective.
Not communicative; not free or apt to impart to others in conversation; reserved; silent; ; hence, not disposed to hold fellowship or intercourse with others; exclusive.