Source : Webster's Revised Unabridged Dictionary (1913)

Plantain \Plan"tain\, n. [F., fr. L. plantago. Cf. {Plant}.]
   (Bot.)
   Any plant of the genus {Plantago}, but especially the {P.
   major}, a low herb with broad spreading radical leaves, and
   slender spikes of minute flowers. It is a native of Europe,
   but now found near the abode of civilized man in nearly all
   parts of the world.

   {Indian plantain}. (Bot.) See under {Indian}.

   {Mud plantain}, a homely North American aquatic plant
      ({Heteranthera reniformis}), having broad, reniform
      leaves.

   {Rattlesnake plantain}, an orchidaceous plant ({Goodyera
      pubescens}), with the leaves blotched and spotted with
      white.

   {Ribwort plantain}. See {Ribwort}.

   {Robin's plantain}, the {Erigeron bellidifolium}, a common
      daisylike plant of North America.

   {Water plantain}, a plant of the genus {Alisma}, having acrid
      leaves, and formerly regarded as a specific against
      hydrophobia. --Loudon.

Plantain \Plan"tain\, n. [Cf. F. plantain-arbre, plantanier, Sp.
   pl['a]ntano, pl['a]tano; prob. same word as plane tree.]
   1. (Bot.) A treelike perennial herb ({Musa paradisiaca}) of
      tropical regions, bearing immense leaves and large
      clusters of the fruits called plantains. See {Musa}.

Source : WordNet®

plantain
     n 1: any of numerous plants of the genus Plantago; mostly small
          roadside or dooryard weeds with elliptic leaves and
          small spikes of very small flowers; seeds of some used
          medicinally
     2: a banana tree bearing hanging clusters of edible angular
        greenish starchy fruits; tropics and subtropics [syn: {plantain
        tree}, {Musa paradisiaca}]
     3: starchy banana-like fruit; eaten (always cooked) as a staple
        vegetable throughout the tropics