Definition of "a priori" [a• pri•o•ri]

• Proceeding from a known or assumed cause to a necessarily related effect; deductive. (adjective)
• Derived by or designating the process of reasoning without reference to particular facts or experience. (adjective)
• Knowable without appeal to particular experience. (adjective)
• Made before or without examination; not supported by factual study. (adjective)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "Yet this rational group-formation can be disrupted under certain circumstances, since it is not of an a priori character."
• "It seems impossible to deny an a priori fighting instinct, especially if one keeps in mind the incredibly picayunish, even silly, occasions of the most serious conflicts."
• "As to whether it “certainly should not” mean this, does Mr. Slatin mean an a priori certainty deducible from the deep structure of the language itself or an observational certainty based on universally accepted, peer-reviewed, reproducible results obtained under controlled conditions?"