summissĭo

ōnis, f.

summitto

I. a letting down, lowering, dropping, sinking (Ciceron.): ex contentione vocis et summissione, Cic. Off. 1, 41, 146: (iterationes) erunt ab hac summissione orationis alienae, id. Or. 25, 85: nec elatio nec summissio, id. Top. 18, 71.
Lewis & Short
A Latin Dictionary, 1879
An open-access project