Reticent, Reticence

I just learned this word.

It means you dont really want to talk to anyone right now. Or doesnt usually socialize.

Im to tired and reticent from work to go out tonight.
The shy student was reticent to speak up even though they knew the answer.

Despite his usualy reticence, he finally spoke up about his concerns at the meeting.

I think other people might use it.