tympanum
tym.pa.num \'tim-p*-n*m\ \-n*\ n or tym.pa.na also tympanums [ML & L; ML,
eardrum, fr. L, drum, architectural panel, fr. Gk tympanon d] pl rum,
kettledrum; akin to Gk typtein to beat 1a1: TYMPANIC MEMBRANE 1a2: the
middle ear 1b: a thin tense membrane covering an organ of hearing of an
insect 1c: a membranous resonator in a sound-producing organ 2a: the
recessed usu. triangular face of a pediment within the frame made b y the
upper and lower cornices 2b: the space within an arch and above a lintel or
a subordinate arch 3: TYMPAN 4: the diaphragm of a telephone