Interstitial:Pertaining to being between things, especially between things that are normally closely spaced. The wordinterstitialis much usedinmedicine and has specific meaning, depending on the context. For instance, interstitial cystitis is a specific type ofinflammationof thebladderwall. Interstitial radiation involves placing放射性material directly into a tumor. Interstitial pneumonia is inflammation of the lung that involves the mesh of lungtissue(alveolarsepta) rather than the air spaces (alveoli).
