'assortative' originates from French, specifically the word 'assortir', where 'as-' (a form of the Latin prefix 'ad-') meant 'to' and 'sortir' (related to Latin 'sors'/'sort-') carried senses of 'lot' or 'arrangement' (here in the sense of matching/arranging).

'assortative' developed from Old French 'assortir' (to agree, to suit or to arrange) and entered English via borrowings such as 'assort' (17th century); the adjectival form 'assortative' and its adverbial derivative 'assortatively' are later formations in modern English.

Initially associated with the idea 'to arrange or match', the sense shifted toward 'characterized by matching or preferential association with similar kinds' (the modern technical sense used in biology and network theory).