Wiktionary
untalkable
a. 1 Not talkative; taciturn; reticent. 2 That cannot be talked of; unspeakable.
Usage examples of "untalkable".
The scintillating and playful essayist whom you pictured to yourself as the most genial and entertaining of companions, turns out to be a shy and untalkable individual, who chills you with his reticence when you chance to meet him.