It's odd that many people who love to gossip about someone else are so reticent about their own lives.
The word reticent is an adjective.
I was reticent about revealing the source of my information. OR She was never reticent about her dislike for country music. OR He was reticent to tell the truth for fear he would be punished.
The suspect was reticent to answer the question because he did the crime.
In Germany people were reticent; if they did talk they could be put to death.
means reserved and unwilling to communicate. The man was reticent when his wife died.
She has always been reticent about discussing her private life. Because of nearly drowning as a child, he's reticent about attending a pool party. A mouth full of fillings makes her reticent to chew gum and eat sticky foods. After a student made laughed at him, Jeff was reticent to volunteer another answer in class.
outgoing...
outgoing
Norm was quite talkative among friends, but reticent among people he did not know well. Note that "reticent" means quiet, but it is often confused with "hesitant" or "reluctant". It is therefore not correct to say someone was "reticent to speak up".
Reserved or reticent.
The antonym of garrulous is reticent, meaning restrained or uncommunicative.
Reticent