The Collaborative International Dictionary of English v.0.48:

Moth \Moth\, n.; pl. Moths (m[o^]thz). [OE. mothe, AS.
   mo[eth][eth]e; akin to D. mot, G. motte, Icel. motti, and
   prob. to E. mad an earthworm. Cf. Mad, n., Mawk.]
   1. (Zool.) Any nocturnal lepidopterous insect, or any not
      included among the butterflies; as, the luna moth; Io
      moth; hawk moth.
      [1913 Webster]

   2. (Zool.) Any lepidopterous insect that feeds upon garments,
      grain, etc.; as, the clothes moth; grain moth; bee moth.
      See these terms under Clothes, Grain, etc.
      [1913 Webster]

   3. (Zool.) Any one of various other insects that destroy
      woolen and fur goods, etc., esp. the larvae of several
      species of beetles of the genera Dermestes and
      Anthrenus. Carpet moths are often the larvae of
      Anthrenus. See Carpet beetle, under Carpet,
      Dermestes, Anthrenus.
      [1913 Webster]

   4. Anything which gradually and silently eats, consumes, or
      wastes any other thing.
      [1913 Webster]

   Moth blight (Zool.), any plant louse of the genus
      Aleurodes, and related genera. They are injurious to
      various plants.

   Moth gnat (Zool.), a dipterous insect of the genus
      Bychoda, having fringed wings.

   Moth hunter (Zool.), the goatsucker.

   Moth miller (Zool.), a clothes moth. See Miller, 3,
      (a) .

   Moth mullein (Bot.), a common herb of the genus Verbascum
      (Verbascum Blattaria), having large wheel-shaped yellow
      or whitish flowers.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Mullein \Mul"lein\, n. [OE. moleyn, AS. molegn.] (Bot.)
   Any plant of the genus Verbascum. They are tall herbs
   having coarse leaves, and large flowers in dense spikes. The
   common species, with densely woolly leaves, is Verbascum
   Thapsus.
   [1913 Webster]

   Moth mullein. See under Moth.

   Mullein foxglove, an American herb (Seymeria macrophylla)
      with coarse leaves and yellow tubular flowers with a
      spreading border.

   Petty mullein, the cowslip. --Dr. Prior.
      [1913 Webster]

WordNet (r) 3.0 (2006):

moth mullein
    n 1: European mullein with smooth leaves and large yellow or
         purplish flowers; naturalized as a weed in North America
         [syn: moth mullein, Verbascum blattaria]