“Development is not an unambiguous concept: there are several meanings (or definitions) of development. Development means growth, and growth is defined as an increase in size or value. This means that something has been present all the time, nothing new is added. Development also means evolution, which derives from the Latin evolve meaning to unfold or to open out. Stage of advancement is [also] listed as a definition of development, advancement being derived from the word advance, which means (among others) to rise or to move forward. [So], If change (e.g. to increase, to open out, to move forward) is the core aspect of development, the next step is to determine the treatment of change (development) in theories on development.”
From: Going the distance: A Non-Linear Approach To Change In Language Development. H.G. Ruhland. Groningen, 1998.