The Collaborative International Dictionary of English v.0.48:

Docile \Doc"ile\, a. [L. docilis,fr. docere to teach; cf. Gr. ?,
   and L. discere to learn, Gr. ? learned, ? knowing: cf. F.
   docile. Cf. Doctor, Didactic, Disciple.]
   1. Teachable; easy to teach; docible. [Obs.]
      [1913 Webster]

   2. Disposed to be taught; tractable; easily managed; as, a
      docile child.
      [1913 Webster]

            The elephant is at once docible and docile. -- C. J.
                                                  Smith.
      [1913 Webster]

WordNet (r) 3.0 (2006):

docile
    adj 1: willing to be taught or led or supervised or directed;
           "the docile masses of an enslaved nation" [ant:
           obstinate, stubborn, unregenerate]
    2: ready and willing to be taught; "docile pupils eager for
       instruction"; "teachable youngsters" [syn: docile,
       teachable]
    3: easily handled or managed; "a gentle old horse, docile and
       obedient" [syn: docile, gentle]

Moby Thesaurus II by Grady Ward, 1.0:

63 Moby Thesaurus words for "docile":
   acquiescent, adaptable, agreeable, alacritous, amenable, apt,
   ardent, biddable, bright, clever, compliant, consenting, content,
   cooperative, disposed, ductile, eager, educable, enthusiastic,
   facile, fain, favorable, favorably disposed, favorably inclined,
   flexible, formable, forward, game, impressionable, in the mind,
   in the mood, inclined, instructable, intelligent, malleable,
   minded, moldable, motivated, plastic, pliable, pliant, predisposed,
   prompt, prone, quick, ready, ready and willing, receptive,
   responsive, ripe for instruction, schoolable, susceptible,
   teachable, thirsty for knowledge, tractable, trainable,
   well-disposed, well-inclined, willed, willing, willinghearted,
   yielding, zealous