1 A premise upon which the fulfillment of an agreement depends; stipulation.
2. A provision making the effect of a legal instrument contingent upon an uncertain event; also; the event itself.
3. Something essential to the appearance or occurrence of something else; prerequisite: as an environmental requirement; the subordinate clause of a conditional sentence.
4. A restricting or modifying factor; qualification.
5. An unsatisfactory academic grade that may be raised by doing additional work.
6. A state of being.
7. Social status; rank; a usually defective state of health.
8. A state of physical fitness or readiness for use.

ETYM Cf. Late Lat. conditionare. Related to Condition.
1. To apply conditioner to in order to make smooth and shiny; of hair.
2. To establish a conditioned response (behaviorism).
3. To put into a better state.