Final answer:
Significant reversibility in spirometry refers to the improvement in lung function after a bronchodilator test. It indicates reversible airway obstruction and is indicative of asthma or another obstructive lung disease.
Step-by-step explanation:
Significant reversibility in spirometry refers to the improvement in lung function after a bronchodilator test. Spirometry is a diagnostic test that measures lung function by assessing the volume and flow of air during inhalation and exhalation. During a bronchodilator test, a bronchodilator medication is administered, and the spirometry test is repeated to see if there is an improvement in lung function. If there is a significant increase in the forced expiratory volume in one second (FEV1) or the forced vital capacity (FVC) after the bronchodilator, it indicates that there is reversible airway obstruction and the patient is likely to have asthma or another obstructive lung disease.