taciturnity

noun

1. the state or quality of being reserved or reticent in conversation.
2. Scots Law. the relinquishing of a legal right through an unduly long delay, as by the silence of the creditor.

n.mid-15c., from Middle French taciturnité, from Latin taciturnitatem (nominative taciturnitas) “a being or keeping silent,” from taciturnus “disposed to be silent,” from tacitus “silent” (see tacit).