The Collaborative International Dictionary of English v.0.48:

Tut \Tut\ (t[u^]t), interj.
   Be still; hush; -- an exclamation used for checking or
   rebuking.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Tut \Tut\, n. [Cf. Sw. tut a point, pipe, tube, Dan. tut a
   cornet.]
   1. An imperial ensign consisting of a golden globe with a
      cross on it.
      [1913 Webster]

   2. A hassock. [Obs. or Prov. Eng.]
      [1913 Webster]

WordNet (r) 3.0 (2006):

tut
    v 1: utter `tsk,' `tut,' or `tut-tut,' as in disapproval [syn:
         tsk, tut, tut-tut]

V.E.R.A. -- Virtual Entity of Relevant Acronyms (February 2016):

TUT
       Transistor Under Test