instillation /in′stilā″shən/ [L, instillare, to drip] , 1. a procedure in which a fluid is slowly introduced into a cavity or passage of the body and allowed to remain for a specific length of time before being drained or withdrawn. It is performed to expose the tissues of the area to the solution, to warmth or cold, or to a drug or substance in the solution. 2. a solution so introduced. Compare infusion, injection, insufflate. −instill, v.
