purr


purr (http://definr.com/purr)

     n : a low vibrating sound typical of a contented cat
     v 1: make a soft swishing sound, as  of a motor working or wings
          flapping [syn: whizz, whiz, whirr, whir, birr]
     2: indicate pleasure by purring; characteristic of cats [syn: {make
        vibrant sounds}]