prior- +

1. In advance, that is, without prior investigation or experience.
2. Presumptive, without examination.
3. Literally, from the former; from what comes before, from cause to effect, deductively [applied to reasoning]; from the general to the particular; self-evident, known independently of experience.
4. Etymology: from a-, ab- + prior, "former".

In a priori reasoning, one works from a known premise (or premises) to a reasonably assumed effect. By extension the phrase is also used to mean, "to the best of one's knowledge". This type of reasoning is the foundation of Western logic, especially that which is embodied in syllogism. Someone has stated that "the great masters of a priori reasoning were Aristotle and Sherlock Holmes."

1. Belief in, or reliance upon, a priori reasoning, arguments, or principles; specifically, the doctrine that knowledge rests upon principles that are self-evident to reason or are presupposed by experience in general.
2. A statement which makes evident a belief in a priori principles.
3. Philosophical belief that knowledge based on general principles may be used to evaluate experience.

Someone who believes in, or relies upon, a priori reasoning, arguments, or principles.

Based on a priori principles.

1. From a general law to a particular instance; valid independently of observation.
2. Existing in the mind prior to and independent of experience, as a faculty or character trait.
3. Not based on prior study or examination; nonanalytic: "He made an a priori judgment."

The term a posteriori has the opposite meaning: from particular instances to a general principle or law; based upon actual observation or upon experimental data and not existing in the mind prior to an experience.

1. Earlier in time or sequence; such as, a prior engagement.
2. More important or basic.
3. Before someone or something in time.
4. An officer in a monastery of a rank below an abbot.
5. A man who is superior in some religious communities.
6. A senior magistrate in some medieval Italian republics; especially, in Florence.

The head of a religious order; in an abbey the prior is next below the abbot.

1. A nun in charge of a priory or ranking next below the abbess of an abbey.
2. A religious house governed by a prior or prioress, often dependent upon an abbey.

1. To arrange or to do in order of priority: "We were learning to prioritize our assignments."
2. To give a high priority to.
3. To organize or deal with something according to its priority.

1. The state of having most importance or urgency: "The judge wanted to give this case priority treatment.
2. Someone or something that is ranked highly in terms of importance or urgency: "It is essential that we get our priorities right."
3. The right to be ranked above others.
4. The situation of having preceded something.

The office of a prior.

A religious residence in a monastery governed by a prior or a convent governed by a prioress.

The vicegerent of a prior; a claustral officer who assists the prior.