a priori

1710, "from cause to effect," a Latin term in logic from c. 1300, in reference to reasoning from antecedent to consequent, based on causes and first principles, literally "from what comes first," from priori, ablative of prior "first" (see prior (adj.)). Opposed to a posteriori. Since c. 1840, based on Kant, used more loosely for "cognitions which, though they may come to us in experience, have their origin in the nature of the mind, and are independent of experience" [Century Dictionary]. Related: Apriorist; apriorism; aprioristic. The a is the usual form of Latin ab "off, of, away from" before consonants (see ab-).

updated on August 10, 2018

Definitions of a priori from WordNet
a priori (adv.)
derived by logic, without observed facts;
a priori (adj.)
based on hypothesis or theory rather than experiment;
A PRIORI (adj.)
involving deductive reasoning from a general principle to a necessary effect; not supported by fact;
an a priori judgment
Etymologies are not definitions. From, not affiliated with etymonline.