[f. L. surdus: see SURD a.] trans. To deaden or dull the sound of, as by a ‘sordine’ or mute. Also Surding vbl. sb. used attrib.
1625. Lisle, Du Bartas, Noe, Ded. ¶¶ j b. To surd it, as young trompeters are wont.
1885. Encycl. Brit., XIX. 70/2. A surding or muting effect produced by impeding the vibration of the strings [of a pianoforte] by contact of small pieces of bull leather.
