An Etymological Dictionary of Astronomy and Astrophysics

1. The act of contradicting; assertion of the contrary or opposite.
   

2. Logic: A statement that is false under all circumstances.
   

Etymology (EN): M.E., from O.Fr. contradiction or directly from L. contradictionem “objection, counterargument,” from contradicere, from contra dicere “to speak against,” from → contra- “against” + dicere “to speak,” akin to Pers. dis, → form.

Etymology (PE): Pâdguyi, literally “speaking against,” from pâd, → counter-, + guyi, from goftan, → logic.