insonorous,a.rare. (ɪnsəʊˈnɔərəs, now freq.ɪnˈsɒnərəs) [in-3.] Not sonorous; giving a dull or muffled sound. 1795Fortnight's Ramble 11 An insonorous voice exclaiming, Damn your day-lights, stop the coach!1889J. M. Robertson Ess.Crit.Meth. 75 The old music-room, with its straitened insonorous instruments.