Source : Webster's Revised Unabridged Dictionary (1913)

Humdrum \Hum"drum`\, a.
   Monotonous; dull; commonplace. ``A humdrum crone.'' --Bryant.

Humdrum \Hum"drum`\, n.
   1. A dull fellow; a bore. --B. Jonson.

   2. Monotonous and tedious routine.

            Dissatisfied with humdrum.            --The Nation.

   3. A low cart with three wheels, drawn by one horse.

Source : WordNet®

humdrum
     adj 1: not challenging; dull and lacking excitement; "an
            unglamorous job greasing engines" [syn: {commonplace},
             {prosaic}, {unglamorous}, {unglamourous}]
     2: tediously repetitious or lacking in variety; "a humdrum
        existence; all work and no play"; "nothing is so
        monotonous as the sea" [syn: {monotonous}]