The first part of this is SoSmother.
The second part of this word (nI') appears in other family related terms (like be'nI'sister and vavnI'grandfather), but it is not clear what its literal meaning is.
Cite this entry
Definition of {SoSnI'}
from the Klingon Language Wiki:
https://klingon.wiki/Word/SoSnI-
Retrieved 19 Aug 2022