semiforbidden

From semi- +‎ forbidden.

semiforbidden (not comparable)

1. (mathematics, physics) Partially forbidden
   • 2016, Zhenzhen Li, Hongyan Zhou, Lei Hao, Shufen Wang, Tuo Ji, Bo Liu, “Strong Optical and UV Intermediate-Width Emission Lines in the Quasar SDSS J232444.80-094600.3: Dust-Free and Intermediate-Density Gas at the Skin of Dusty Torus ?”, in arXiv‎:

     The IEL component is presented in different emission lines, including the permitted lines \lya\ ${\displaystyle \lambda }$1216, \civ\ ${\displaystyle \lambda }$1549, semiforbidden line \ciii\ ${\displaystyle \lambda }$1909, and forbidden lines \oiii\ ${\displaystyle \lambda \lambda }$4959, 5007.