The Collaborative International Dictionary of English v.0.48:

Develop \De*vel"op\ (d[-e]*v[e^]l"[o^]p), v. t. [imp. & p. p.
   Developed; p. pr. & vb. n. Developing.] [F. d['e]veloper;
   d['e]- (L. dis-) + OF. voluper, voleper, to envelop, perh.
   from L. volup agreeably, delightfully, and hence orig., to
   make agreeable or comfortable by enveloping, to keep snug
   (cf. Voluptuous); or. perh. fr. a derivative of volvere,
   volutum, to roll (cf. Devolve). Cf. Envelop.] [Written
   also develope.]
   1. To free from that which infolds or envelops; to unfold; to
      lay open by degrees or in detail; to make visible or
      known; to disclose; to produce or give forth; as, to
      develop theories; a motor that develops 100 horse power.
      [1913 Webster]

            These serve to develop its tenets.    --Milner.
      [1913 Webster]

            The 20th was spent in strengthening our position and
            developing the line of the enemy.     --The Century.
      [1913 Webster]

   2. To unfold gradually, as a flower from a bud; hence, to
      bring through a succession of states or stages, each of
      which is preparatory to the next; to form or expand by a
      process of growth; to cause to change gradually from an
      embryo, or a lower state, to a higher state or form of
      being; as, sunshine and rain develop the bud into a
      flower; to develop the mind.
      [1913 Webster]

            The sound developed itself into a real compound.
                                                  --J. Peile.
      [1913 Webster]

            All insects . . . acquire the jointed legs before
            the wings are fully developed.        --Owen.
      [1913 Webster]

   3. To advance; to further; to prefect; to make to increase;
      to promote the growth of.
      [1913 Webster]

            We must develop our own resources to the utmost.
                                                  --Jowett
                                                  (Thucyd).
      [1913 Webster]

   4. (Math.) To change the form of, as of an algebraic
      expression, by executing certain indicated operations
      without changing the value.
      [1913 Webster]

   5. (Photog.) To cause to become visible, as an invisible or
      latent image upon plate, by submitting it to chemical
      agents; to bring to view.
      [1913 Webster]

   To develop a curved surface on a plane (Geom.), to produce
      on the plane an equivalent surface, as if by rolling the
      curved surface so that all parts shall successively touch
      the plane.

   Syn: To uncover; unfold; evolve; promote; project; lay open;
        disclose; exhibit; unravel; disentangle.
        [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

developing \developing\ adj.
   1. not industrialized but undergoing industrialization; --
      sometimes used as a euphemism for "undeveloped"; -- of
      nations.

   Syn: underdeveloped.
        [WordNet 1.5]

   2. [pr. p. of develop (WN definition 5)] becoming or
      arising; as, the rushing yellow of the developing day.
      [WordNet 1.5]

The Collaborative International Dictionary of English v.0.48:

developing \developing\ n.
   the process of treating a photosensitive material with
   chemicals in order to make a latent image visible.

   Syn: development.
        [WordNet 1.5 +PJC]

WordNet (r) 3.0 (2006):

developing
    adj 1: relating to societies in which capital needed to
           industrialize is in short supply [syn: developing,
           underdeveloped]
    n 1: processing a photosensitive material in order to make an
         image visible; "the development and printing of his
         pictures took only two hours" [syn: development,
         developing]