1) Expanse 
A spatium or anatomic space is a space (cavity or gap) in anatomy. Anatomic spaces are often landmarks to find other important structures. When they fill with gases (such as air) or liquids (such as blood) in pathological ways, they can suffer conditions such as pneumothorax, edema, or pericardial effusion. Many anatomic spaces are potential space...
Synonym: space. ... Origin: L. ... (05 Mar 2000) ... 
(spa´she-әm) Latin word meaning space; a term used in anatomy.
Type: Term Pronunciation: spā′shē-ŭm, -shē-ă Synonyms: space
(Latin) expanse.