2  definitions  found 
 
  From  Webster's  Revised  Unabridged  Dictionary  (1913)  [web1913]: 
 
  Tympanum  \Tym"pa*num\,  n.;  pl  E.  {Tympanums},  L.  {Tympana}. 
  [L.,  a  kettledrum,  a  drum  or  wheel  in  machines,  the 
  triangular  area  in  a  pediment,  the  panel  of  a  door,  Gr  ?,  ?, 
  fr  ?  to  strike,  beat  See  {Type},  and  cf  {Timbrel}.] 
  1.  (Anat.) 
  a  The  ear  drum,  or  middle  ear.  Sometimes  applied 
  incorrectly  to  the  tympanic  membrane.  See  {Ear}. 
  b  A  chamber  in  the  anterior  part  of  the  syrinx  of  birds. 
 
  2.  (Zo["o]l.)  One  of  the  naked,  inflatable  air  sacs  on  the 
  neck  of  the  prairie  chicken  and  other  species  of  grouse. 
 
  3.  (Arch.) 
  a  The  recessed  face  of  a  pediment  within  the  frame  made 
  by  the  upper  and  lower  cornices,  being  usually  a 
  triangular  space  or  table. 
  b  The  space  within  an  arch,  and  above  a  lintel  or  a 
  subordinate  arch,  spanning  the  opening  below  the  arch. 
 
  4.  (Mech.)  A  drum-shaped  wheel  with  spirally  curved 
  partitions  by  which  water  is  raised  to  the  axis  when  the 
  wheel  revolves  with  the  lower  part  of  the  circumference 
  submerged,  --  used  for  raising  water,  as  for  irrigation. 
 
  From  WordNet  r  1.6  [wn]: 
 
  tympanum 
  n  1:  the  main  cavity  of  the  ear;  between  the  eardrum  and  the 
  inner  ear  [syn:  {middle  ear},  {tympanic  cavity}] 
  2:  the  membrane  in  the  ear  that  vibrates  to  sound  [syn:  {eardrum}, 
  {tympanic  membrane}] 
  3:  a  large  hemispherical  brass  or  copper  drum  with  a  drumhead 
  that  can  be  tuned  by  adjusting  the  tension  on  it  [syn:  {kettle}, 
  {kettledrum},  {tympani},  {timpani}] 

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