" taciturnity "

 [ "taciturn" ]

1: an adj that describes someone who doesn't talk too much

  * e.g.,  ... Even though she is so taciturn, I know that deep inside, she always wanna make friends with other people. 

 [ "Taciturn" ]

1: Someone who isn’t particularly-socially-inclined (at all) and only talks when they have to. Restrained, reticent.

  * e.g.,  ... Person A: ‘I tried milking a few personal musings out of him as he was filling out his insurance form but I might as well have been talking to a log of ice. Is he just naturally quite introverted or is there something up with him?’ Person B: ‘no, he’s actually quite outgoing but he has a tendency to be quite taciturn around people who’s not that familiar with. He doesn’t do small-talk or say any more than he absolutely has to around people he doesn’t know that well but he’s not especially-introverted, nor does he dislike you, per se (I doubt it). He probably just doesn’t care to get to know you better.’