Secosteroid
（重定向自Secosteroids）
![Cholecalciferol (vitamin D3), an example of a 9,10-secosteroid. The hydroxyl group (HO-) is in position C3 of the parent steroid A-ring. The triene substructure attached to the ring bearing the hydroxyl group is a result of the ring scission (cleavage) giving rise to this secosteroid.](/Images/godic/202502/10/Cholecalciferol.svg1346.png")
![The parent steroid skeleton. The B-ring of the parent steroid is broken between C9 and C10 to yield the vitamins D.](/Images/godic/202502/10/Trimethyl_steroid-nomenclature.svg1346.png")
A secosteroid (sec·o·ster·oid, sek'ō-stēr'oyd) is a type of steroid with a "broken" ring. The word secosteroid derives from the verb Latin:secare meaning "to cut", and Latin:stere of steroid, meaning "solid, three-dimensional". Secosteroids are alternatively described as a subclass of steroids or derived from steroids.