Obex

Part of speech: noun

Pronunciation: /ˈəʊ.bɛks/

Definitions

1. A barrier formed at the back of a specific organ that serves to delineate areas
2. This term describes a structural feature that functions to obstruct or delimit biological spaces within organisms
3. A structure acting as a dividing point within an organ to separate regions

Etymology: In Latin, "obex" meant "barrier" or "wall," a bar or bolt that blocked a gate or door. That plain physical sense is still visible in the word's modern use. In anatomy, an obex is a structural feature that closes off or marks a boundary within the body, most famously the point on the floor of the fourth ventricle of the brain where the central canal of the spinal cord opens into that cavity. The word reached English as a direct borrowing from Latin, so it kept the original sense of something that stops passage. Its use in English stays firmly within the technical vocabulary of anatomy and neuroscience, where it names a boundary rather than a physical gate.