Hum v. i. [imp. & p. p. Hummed p. pr. & vb. n. Humming ]
  1. To make a low, prolonged sound, like that of a bee in flight; to drone; to murmur; to buzz; as, a top hums.
     Still humming on, their drowsy course they keep.   --Pope.
  2. To make a nasal sound, like that of the letter m prolonged, without opening the mouth, or articulating; to mumble in monotonous undertone; to drone.
  The cloudy messenger turns me his back,
  And hums.   --Shak.
  3.  To make an inarticulate sound, like h'm, through the nose in the process of speaking, from embarrassment or a affectation; to hem.
  4. To express satisfaction by a humming noise.
     Here the spectators hummed.   --Trial of the Regicides.
  Note: ☞ Formerly the habit of audiences was to express gratification by humming and displeasure by hissing.
  5. To have the sensation of a humming noise; as, my head hums, -- a pathological condition.
  hum
       n 1: the state of being or appearing to be actively engaged in an
            activity; "they manifested all the busyness of a pack of
            beavers"; "there is a constant hum of military
            preparation" [syn: busyness]
       2: an Islamic fundamentalist group in Pakistan that fought the
          Soviet Union in Afghanistan in the 1980s; now operates as
          a terrorist organization primarily in Kashmir and seeks
          Kashmir's accession by Pakistan [syn: Harkat-ul-Mujahidin,
           Harkat ul-Ansar, HUA, Harkat ul-Mujahedeen, Al
          Faran, Movement of Holy Warriors]
       3: a humming noise; "the hum of distant traffic" [syn: humming]
       v 1: sing with closed lips; "She hummed a melody"
       2: be noisy with activity; "This office is buzzing with
          activity" [syn: buzz, seethe]
       3: sound with a monotonous hum [syn: thrum]
       4: make a low continuous sound; "The refrigerator is humming"
       [also: humming, hummed]