The word taciturn has nothing to do with any other kind of a turn, but comes to us almost unchanged from the Latin taciturnus, “silent,” through tacitus, the past participle of tacere, “to be silent.”
Although taciturn, today, rarely implies the absolute silence suggested by its ancestor (meaning, rather, “disinclined to conversation, uncommunicative”), the expression of this quality has been retained in tacit, which is also derived from tacitus, tacere.
