Thrum \Thrum\, v. t. [imp. & p. p. {Thrummed}; p. pr. & vb. n. {Thrumming}.] 1. To furnish with thrums; to insert tufts in; to fringe. [1913 Webster] Are we born to thrum caps or pick straw? --Quarles. [1913 Webster] 2. (Naut.) To insert short pieces of rope-yarn or spun yarn in; as, to thrum a piece of canvas, or a mat, thus making a rough or tufted surface. --Totten. [1913 Webster]