abbreviationäsäs
1(in calculating dates) Old Style.
2Computing
Operating system.
4(in the UK) Ordnance Survey.
5(as a size of clothing) outsize.
nounPlural ora, Plural ossa äsäs
Anatomy A bone (used chiefly in Latin names of individual bones, e.g. os trapezium).
〔剖〕骨（主要用于骨的拉丁名，如 os trapezium ）
Example sentencesExamples
- Besides this unambiguous distinguishing character, a second, derived character, exists which is particular to the Carnivora: in the wrist the joint bones, scaphoid, lunate, and os centrale, are fused.
- In this group, the cortex of the os sacrum was destroyed and had a spongelike rather than compact appearance.
nounPlural ora, Plural ossa äsäs
Anatomy An opening or entrance to a passage, especially one at either end of the cervix of the uterus.
〔剖〕口（尤指子宫颈的两头之一）
Example sentencesExamples
- The distance between the internal and external os was measured both as a straight line and also as a curved line along the endocervical canal.
- The internal os closes by 3 days, the external os by 3 weeks.
Origin
Mid 18th century: from Latin, 'mouth'.
The chemical element osmium.