1. shun the company of others; - Example: "The new student keeps to herself"
2. withhold information; - Example: "I kept your little secret to myself all these years"
WordNet (r) 3.0 (2006):
keep to oneself
v 1: shun the company of others; "The new student keeps to
herself"
2: withhold information; "I kept your little secret to myself
all these years"