Ostium
/ˈɒs.ti.əm/noun
An opening or passage into a cavity, especially in anatomical or medical terminology.
Did you know?Latin *ostium* could mean a door, entrance, river mouth, or bodily opening, while its relative *os* meant “mouth,” preserving a striking doorway metaphor in modern anatomy.
Etymological Timeline
Proto-Indo-European
PIE
*h₁ōs
“Mouth or opening”
Ancient Latin
Latin
ōs
“Mouth; opening; entrance”
Classical Latin
Latin
ostium
“Door, doorway, entrance, or mouth of a river”
Late Latin
Latin
ostium
“An opening or access point, including bodily passages”
17th Century
English
ostium
“An anatomical opening or entrance into a cavity”
Modern English
English
ostium
“A named anatomical opening or passage”