Diminutive

n.
  1. Something of very small size or value; an insignificant thing.
  2. (Gram.) A derivative from a noun, denoting a small or a young object of the same kind with that denoted by the primitive; as, gosling, eaglet, lambkin.

The word sometimes denotes a derivative verb which expresses a diminutive or petty form of the action, as scribble.