converse -
of words so related that one reverses the relation denoted by the other; "`parental' and `filial' are converse terms"
= synonym
= antonym
= relatert ord
Wiktionary
Substantiv
converse -
The opposite or reverse.
converse -
Of a proposition or theorem of the form: given that "If A is true, then B is true", then "If B is true, then A is true. " equivalently: given that "All Xs are Ys", then "All Ys are Xs".