reticent
Not wanting to talk or share much about yourself.
Reticent means reluctant to speak or share information, especially about yourself or your feelings. A reticent person holds back in conversation, choosing words carefully and revealing little. If your friend seems reticent about how her soccer game went, she's not eager to discuss it, maybe staying quiet or giving short answers.
Being reticent is different from being shy. Shy people might want to talk but feel nervous. Reticent people actively choose silence or brevity, often because they value privacy or discretion. A reticent student might excel in class but rarely volunteer personal stories during group discussions.
The word often suggests a thoughtful, careful quality rather than weakness. Some cultures value reticence, seeing it as dignified restraint rather than unfriendliness. A reticent leader might listen more than talk, speaking only when they have something important to say.
You might encounter reticence when asking someone about a difficult topic. If your teacher seems reticent when you ask about changes at school, she's probably choosing to keep certain information private, at least for now. Understanding someone's reticence means respecting that they have reasons for not sharing everything, and that silence can sometimes be its own kind of communication.