development has 8 distinct synonyms spread across 4 of its 9 senses. Each sense below keeps its own list, because a synonym belongs to a meaning and not to a word: swapping one sense's substitute into another sense's sentence is how a thesaurus makes writing worse. Its one recorded opposite is nondevelopment.
Counts are distinct word forms across every sense. A synonym that appears under three senses is counted once here and shown three times below, under each sense it belongs to.
act of improving by expanding or enlarging or refining
“he congratulated them on their development of a plan to meet the emergency”
(biology) the process of an individual organism growing organically; a purely biological unfolding of events involved in an organism changing gradually from a simple to a more complex level
“he proposed an indicator of osseous development in children”
a recent event that has some relevance for the present situation
“recent developments in Iraq”
the act of making some area of land or water more profitable or productive or useful
“the development of Alaskan resources”
a district that has been developed to serve some purpose
“such land is practical for small park developments”
a state in which things are improving; the result of developing (as in the early part of a game of chess)
“after he saw the latest development he changed his mind and became a supporter”
processing a photosensitive material in order to make an image visible
“the development and printing of his pictures took only two hours”
(music) the section of a composition or movement (especially in sonata form) where the major musical themes are developed and elaborated
Synonyms, antonyms and the broader and narrower relations for development come from Princeton University’s WordNet. Full sources and licences.