Definition of drumbling in English:
drumbling
noun ˈdrʌmb(ə)lɪŋˈdrʌmblɪŋ
rare The action of drumble; droning, blathering.
adjective ˈdrʌmb(ə)lɪŋˈdrʌmblɪŋ
rare Origin
Late 16th century; earliest use found in Thomas Nashe (d. c1601), writer. From drumble + -ing.