Taciturn means saying very little by nature. Not sulking — simply not a talker.
The permanence is the point, since somebody taciturn is like that always, which is what separates it from silent or quiet on a particular occasion. It is a neutral or even respectful word, and a taciturn man in fiction is usually to be trusted. It comes from the same Latin root as tacit, meaning understood without being said. Its opposite is garrulous, meaning tiresomely talkative.
1adjectivetaciturnHabitually saying very little.
“He was a taciturn man who answered in single words.”
Taciturn came into English backwards. Taciturnity arrived first, from Latin taciturnitās, and the adjective was cut out of the noun afterwards. Behind both is tacitus, silent, which also gives tacit.
French
taciturne
Latin
taciturnitās
Middle English
taciturnite
English, today
taciturn
Built from
a back-formation from taciturnity, from Middle English taciturnite, from Latin taciturnitās; or alternatively from French taciturne, likely reinforced by Latin taciturnus, from tacitus (“secret, tacit”).
Etymology from Wiktionary, CC BY-SA