tacit Look up tacit at Dictionary.com
1604, from Fr. tacite, from L. tacitus "that is passed over in silence, done without words, assumed, silent," prop. pp. of tacere "to be silent," from PIE base *tak- "to be silent" (cf. Goth. þahan, O.N. þegja "to be silent," O.N. þagna "to grow dumb," O.S. thagian, O.H.G. dagen "to be silent"). The musical instruction tacet is the 3rd person present sing. of the L. verb.