An Etymological Dictionary of Astronomy and Astrophysics

To state or assert positively; maintain as true.

Etymology (EN): M.E. affermen, affirmen “to decide upon; to state positively,” from O.Fr. afermer “affirm, confirm; strengthen,” from L. affirmare “to make steady, strengthen,” from → ad- “to” + firmare “strengthen, make firm,” from firmus, → firm.

Etymology (PE): Baedešidan, from bar- “upon, to,” + deš, → firm, + infinitive suffix -idan.