'desegregative' originates from modern English, formed from the verb 'desegregate' + the adjectival suffix '-ive'.

'desegregate' changed from Latin-rooted elements: it is formed from the prefix 'de-' + 'segregate' (from Latin 'segregare'). 'Segregare' comes from Latin 'se-' (apart) + 'gregare' (to gather, from 'grex' meaning 'flock'), and through English formation the modern adjective 'desegregative' developed.

Initially, the Latin root 'segregare' referred to putting apart (separating a flock); over time the compounded English form 'desegregate' came to mean removing or reversing separation in social contexts, and 'desegregative' now describes things that promote or relate to that removal of separation.