taciturn

Etymology

Back-formation from taciturnity, from Middle English taciturnite, from Latin taciturnitas; or alternatively from French taciturne, likely reinforced by Latin taciturnus, from tacitus (“secret, tacit”).

adj

1. Silent; temperamentally untalkative; disinclined to speak.
   The two sisters could hardly have been more different, one so boisterous and expressive, the other so taciturn and calm.
   We are each of an unsocial, taciturn disposition, unwilling to speak, unless we expect to say something that will amaze the whole room, and be handed down to posterity with all the eclat of a proverb. 1813, Jane Austen, Pride and Prejudice, Chapter 18
   We spent a lot of time up on the staging of the great furnaces, trying to pick up the tricks of the trade from the taciturn furnacemen who sat around placidly smoking, or chewing twist, and occasionally throwing in more pig iron to the molten white-hot metal. 1945 January and February, A Former Pupil, “Some Memories of Crewe Works—III”, in Railway Magazine, page 14