2. Noun. (medicine) Specifically the tissue between the pulmonary alveoli and the bloodstream. ¹
3. Noun. (philosophy) A state between systems or spaces. ¹
¹ Source: wiktionary.com
Medical Definition of Interstitium
1. A small area, space, or gap in the substance of an organ or tissue. See: connective tissue. Synonym: interstice. Origin: L. (05 Mar 2000)