Lewis & Short

mussĭto, 1, v. freq. n. and a. [musso].

  1. I. Neutr., to be silent, keep quiet, not let one’s self be heard; to speak in an undertone, to mutter, grumble (not in Cic. or Cæs.): si sapis, mussitabis, Plaut. Mil. 2, 5, 65: sub lectis latentes metu mussitant, id. Cas. 3, 5, 33: ita clam quidam mussitantes, Liv. 1, 50: cum David vidisset servos suos mussitantes, Vulg. 2 Reg. 12, 19: contra nos, id. Exod. 16, 7.
  2. II. Act., to say in a low tone, to mutter, murmur any thing: to be silent respecting, to take no notice of a thing: ego (haec) mecum mussito, Plaut. Mil. 3, 1, 119; id. Truc. 2, 2, 57; 2, 6, 10.
    With rel.-clause: malo ambigere bonos, quam ob rem id non meruerim, quam, quod est gravius, cur impetraverim, mussitare, Amm. 14, 6, 8: accipienda et mussitanda injuria adulescentium est, is to be borne in silence, Ter. Ad. 2, 1, 53: timorem, App. Mag. p. 320.