A mode or state of being: "The Organization Man survives as a modern classic because it captures a permanent part of our social condition\u201d ( Robert J. Samuelson). See Synonyms at state. A state of health. A state of readiness or physical fitness. A disease or physical ailment: a heart condition. Social position; rank. One that is indispensable to the appearance or occurrence of another; prerequisite: Compatibility is a condition of a successful marriage. One that restricts or modifies another; a qualification. Existing circumstances: Conditions in the office made concentration impossible. Grammar The dependent clause of a conditional sentence; protasis. Logic A proposition on which another proposition depends; the antecedent of a conditional proposition. Law A provision making the effect of a legal instrument contingent on the occurrence of an uncertain future event. Law The event itself. An unsatisfactory grade given to a student, serving notice that deficiencies can be made up by the completion of additional work. Obsolete Disposition; temperament. To make dependent on a condition or conditions. To stipulate as a condition. To render fit for work or use. To accustom (oneself or another) to; adapt: had to condition herself to long hours of hard work; conditioned the troops to marches at high altitudes. To air-condition. To give the unsatisfactory grade of condition to. Psychology To cause an organism to respond in a specific manner to a conditioned stimulus in the absence of an unconditioned stimulus. To replace moisture or oils in (hair, for example) by use of a therapeutic product.