"habitually silent," 1771, back-formation from taciturnity, or from French taciturne (15c.), from Latin taciturnus "not talkative, noiseless."
Entries linking to taciturn
taciturnity n.
mid-15c., from Old French taciturnité, from Latin taciturnitatem (nominative taciturnitas) "a being or keeping silent," from taciturnus "disposed to be silent," from tacitus "silent" (see tacit).